Labour's manifesto will offer a vision of a Britain in which "nobody is ignored, nobody is forgotten, nobody is left behind", Jeremy Corbyn has said.
Mr Corbyn was speaking after a meeting of the party's shadow cabinet and national executive committee unanimously approved the document, believed to set out plans to nationalise key industries and reverse years of austerity.
Labour's launch plans were thrown into disarray by the leak of a draft version of the document to national newspapers.
British Prime Minister Theresa May said the leaked draft suggested Labour wanted to take Britain "back to the past".
Mr Corbyn predicted the policies would prove "very popular" and said they amounted to "an offer that will transform the lives of many people in our society and ensure that we have a government in Britain on June 8 that will work for the many, not the few, and give everyone in our society a decent opportunity and a decent chance, so nobody is ignored, nobody is forgotten and nobody is left behind."
According to the leaked document obtained by the Daily Mirror and Telegraph, a Corbyn government would:
:: Renationalise railways as each private franchise expires, with fares frozen and guards put back on driver-only trains.
:: Establish publicly-owned bus companies.
:: Return Royal Mail to public ownership following the coalition government's "historic mistake" of selling it off.
:: Take energy "back into public ownership" by setting up a rival to the existing Big Six private firms.
See the key points from the leaked Labour manifesto at the bottom of this article
To pay for the policy pledges, Labour has already announced plans to hike corporation tax to 26% by 2022, bringing in an extra £20 billion for the Exchequer, and indicated people earning more than £80,000 will face tax rises.
The manifesto indicates a further levy on firms "with high numbers of staff on very high pay".
In an effort to bridge party divides over Trident, it commits Labour to the nuclear deterrent, but in a nod to Mr Corbyn's opposition to the weapons it says "any prime minister should be extremely cautious about ordering the use of weapons of mass destruction which would result in the indiscriminate killing of millions of innocent civilians".
Despite Mr Corbyn's declaration that the Brexit question was "settled" by last year's referendum, the document states withdrawing from the EU without a deal would be the "worst possible" outcome and would be rejected as a "viable" option.
The document also declines to set a numerical target for net migration.
Mr Corbyn vowed the final manifesto would include "costings of all the pledges and promises that we make".
He said the draft was the result of "the most informed, interesting, sensible discussion and debate" within the party and had been amended at Thursday's meeting, attended by senior figures from Labour and trade unions.
It is due for its formal publication next week.
One party insider told the Press Association the leaked draft was an earlier version which had been subject to rewriting in at least one section before the gathering.
The Labour leader pulled out of a planned campaign event as the party fought to contain the damage from the extraordinary leak.
Disarray surrounding the security breach was heightened when a BBC cameraman was injured by a car carrying Mr Corbyn to the meeting.
Tories branded the manifesto a recipe for taxes and borrowing which would put the UK on the "road to ruin".
Mrs May told Channel 4 News the "shambolic" way the document emerged "shows the sort of chaos that we would see from a Labour government".
She added: "If you take their manifesto overall, actually, what they are suggesting is taking us back to the past.
"What I'm interested in is dealing with the challenges that we face today but making a better future for this country."
Leaving the meeting, Unite union boss Len McCluskey said the manifesto was "brilliant" and claimed there was "complete unanimity" among those present about its contents.
Shadow chancellor John McDonnell insisted it was "a modernising, exciting new modern manifesto".
Liberal Democrat leader Tim Farron told the Press Association: "It doesn't matter whether it was leaked or not leaked, the Labour manifesto ceased to be relevant in any way, shape or form the moment Jeremy Corbyn and his party held hands with Ukip and Theresa May and voted for the triggering of Article 50."
Key points from the leaked Labour manifesto:
:: Railways brought back into public ownership as franchises expire.
:: Under public ownership fares will be frozen, driver-only operation ended and free WiFi introduced across the network.
:: HS2 will be completed and will link with a "Crossrail of the North".
:: Energy market partially brought back into public ownership.
:: Creation of at least one publicly owned energy company in every region of the UK.
:: Central government control of the grid and distribution.
:: Cap average household dual fuel bills at £1,000 a year.
:: Ban fracking.
:: Tuition fees abolished and maintenance grants reintroduced for university students.
:: Labour "accepts the referendum result" and intends to build a close new relationship with Europe "not as members but as partners".
:: Retain benefits of single market and customs union.
:: Immediately guarantee existing rights of EU nationals living in Britain and secure reciprocal rights for UK citizens living in another EU country.
:: No "no deal" option at the end of Article 50 negotiations, with "transitional arrangements" negotiated instead to avoid cliff-edge.
:: Scrap Great Repeal Bill and replace with EU Rights and Protections Bill.
:: Labour "believes in fair rules and reasonable management of migration" and will not make "false promises" on numbers.
:: Income thresholds for family members replaced with an obligation to "survive without recourse to public funds".
:: Creation of a Migrant Impact Fund to support public services in host communities. It will be funded by visa levies and a contributory element from residence visas for high net worth individuals.
:: More than £6 billion extra annual funding for the NHS through increased income tax for top 5% earners, increased tax on private medical insurance and halving management consultants' fees.
:: Mental health budgets ring-fenced.
:: Pay cap scrapped.
:: EU NHS workers' rights immediately protected.
:: NHS Sustainability and Transformation Plans halted.
:: Creation of a new "quality, safety and excellence regulator" called NHS Excellence.
:: Move towards creation of a National Care Service.
:: Investment of £8 billion in services over the next parliament, including £1 billion in the first year.
:: Improve conditions for care workers.
:: 15-minute care visits scrapped.
:: Carer's Allowance increased to be in line with Jobseeker's Allowance.
:: Creation of a Ministry of Labour to deliver investment in enforcing workers' rights.
:: Repeal Trade Union Act and introduce "sectoral collective bargaining" through unions.
:: Zero hours contracts outlawed.
:: Unpaid internships banned.
:: Employers stopped from only recruiting from overseas.
:: Bring minimum wage in line with living wage - at least £10 by 2020.
:: Rights for all workers to have access to trade union.
:: Paternity leave doubled to four weeks and paternity pay increased.
:: Protections for women on maternity leave strengthened.
:: Four new public holidays to mark patron saints' days.
:: Public inquiry into blacklisting.
:: A 20:1 limit on gap between the lowest and highest paid workers in companies given Government contracts.
:: Reduce pay inequality through legislation by introducing an "excessive pay levy" on companies with high numbers of staff on high pay.
:: No income tax rises for those earning below £80,000 a year.
:: Large corporations will pay "a little more" tax while remaining competitive with cash paying for education and skills budgets.
:: Extra powers for HMRC to chase individuals and companies who avoid tax.
:: "Triple lock" guaranteed throughout next parliament or kept to at least 2.5%.
:: Winter fuel allowance and free bus passes kept as universal benefits.
:: Compensation for women born in 50s who had state pension age changed without fair notification.
:: Invest to build one million new homes, including 100,000 council and housing association homes by the end of next parliament.
:: Rent rises capped to inflation and legal minimum standards in properties for rent.
:: 4,000 homes for people with history of rough sleeping.
:: Scrap bedroom tax and reinstate housing benefit for under-21s.
:: Review cuts to Universal Credit and limits on payments to first two children of families.
:: Borrow to invest £250 billion over 10 years on energy, transport and digital infrastructure.
:: Improve 4G mobile coverage and invest to bring uninterrupted 5G to all urban areas, major roads and railways
:: Lower voting age to 16.
:: Support the renewal of Trident.
:: Keep defence spending as 2% of GDP.
:: 10,000 more police officers for community beats.
:: Conduct major review of counter-terror Prevent programme.