Update 4.52pm: French President Emmanuel Macron has vowed not to allow the re-establishment of the "Jungle" camp of migrants in Calais.
His promise came as he visited the Channel port ahead of a UK-France summit at which reports suggest he will seek to renegotiate Britain's role in dealing with migrants gathered there.
Mr Macron said the current "Dublin rules", under which refugees are required to seek asylum in the first safe country they reach, were "unsatisfactory" and called for an "integrated" EU system to deal with the problem.
Hundreds of asylum seekers hoping to cross the Channel remain in the area, more than a year after authorities dismantled the town's sprawling Jungle camp.
The president met Calais mayor Natacha Bouchart and organisations working with migrants on Tuesday, just two days before talks with Prime Minister Theresa May.
Aid groups have labelled the visit a "political show", while organisation L'Auberge des Migrants declined to meet Mr Macron "to show our profound disagreement with the upcoming immigration law".
One refugee called on the president to show "pity" for the plight of migrants in his policy.
Mr Macron said that Calais had become "a dead end for thousands of women and men who have spent years on the road".
Update 1.41pm: French president Emmanuel Macron has said he wants to negotiate with the UK over better police cooperation to handle migrants in the French port of Calais - and is also seeking more money from Britain to help develop the city.
Mr Macron is visiting the northern city, where many migrants attempt to sneak across the Channel.
In a speech to security forces in the city, Mr Macron also said he wants the UK to take in more unaccompanied minors.
Mr Macron is scheduled to meet Prime Minister Theresa May in Sandhurst on Thursday.
He said France is doing "everything" to prevent migrants from illegally entering the UK, insisting: "Calais is not a back door to England."
The city is the closest point between France and Britain, with two cross-Channel transport systems, the Eurotunnel and ferries.
Earlier: French president Emmanuel Macron has visited a migrant centre in northern France as he prepares to press the UK to do more to help deal with people who converge on the Calais region in hopes of crossing the Channel.
Mr Macron talked briefly with Sudanese migrants at the centre in Croisilles, home to 63 people.
He also questioned officials about measures to speed up processing for migrants who agree to apply for asylum in France.
The French president also asked about migrants who abandon such centres to try to sneak across the Channel instead.
Guillaume Alexandre, the head of the association managing three facilities in the Pas-de-Calais region, said nearly 70% of migrants there leave before filing any paperwork in France.
Mr Macron will travel to Calais later on Tuesday. On Thursday, he will meet Prime Minister Theresa May to discuss accords that effectively place the British border in Calais.