Update 10.45pm: Michel Barnier has warned the UK that if they don't support Theresa May's deal in the next few days their options going forward will be limited.
Speaking in Brussels, EU chief Brexit negotiator said: "If the UK Parliament does not vote in favour of the Withdrawal Agreement in the coming days only two options would remain.
Mr Barnier said it "would be the responsibility" of the UK Government to choose between leaving without an agreement or seeking an extension.
He added: "No deal was never our desired or intended scenario.
"But the EU is now prepared.
He said no deal "becomes day after day more likely".
Mr Barnier said: "The UK may ask for another extension. Such an extension would carry significant risks for the EU.
"Therefore a strong justification would be needed.
"Many businesses in the EU warn us against the cost of extending uncertainty.
Mr Barnier said that the EU would be willing to enter a relationship with the UK similar to the arrengement between Europe and Norway.
He said: "We have always said that we can accept a customs union, or relationship along the style of the Norway model.
"In fact, however, the Political Declaration today can accommodate all of these options already.
"It leaves the door open for a variety of outcomes.
"But if the UK so wishes we are ready to rework the Political Declaration."
Mr Barnier later told the European Parliament's Committee on Foreign Affairs that no-deal would disrupt EU/UK security co-operation.
"We need to be aware of the implications of a no-deal for our security partnership," he told MEPs.
"There will be a break in the level of talks, less mutual commitment, risks to intelligence pooling. There might be inconsistencies in applying sanctions regimes because of a low level of co-operation.
Mr Barnier said: "No-deal for some time poses the threat of there being no organised framework... Come what may, we must fend off the risk of strategic divergence."
Michel Barnier said the UK was in a "crisis" which went beyond the question of Brexit.
He told the Committee: "I don't think I need to go on at great length about the nature of what is going on in the UK, the impasse or political crisis they might be experiencing.
"More deeply, it is not just about the question of Brexit. I don't think it's just about the question of Brexit and the agreement that's on the table and the backstop for Ireland.
"It is more broad than that. Somewhere along the line, it is a crisis that equally could have sprung up in another country.
"In my country as well, there are questions about what our relationship is to the world, what is our place in the EU, what is our economic model. These are all things coming out as a result of the British debate as well."
Mr Barnier warned that a no-deal Brexit would not mean an end to wrangling over the Irish border, citizens' rights and the UK's financial liabilities, which he predicted would restart in a more difficult atmosphere.
In response to a question from a British MEP on the Committee on Foreign Affairs, he said: "If there is no deal, the atmosphere will be different. The lack of a deal means a lack of faith, a lack of deal means a rupture in confidence between us.
"I think we have to have confidence in order to build a future relationship. Your country will have to have relations with us and we with them.
"There won't be many months passing before the UK will start asking for negotiations on a free trade agreement or other issues, like transport.
"The topics of Brexit will still be there - Ireland, the financial resolution, the legal obligations of the UK, the issues of citizens and citizens' rights. These are questions we will put again and again.
"If there is no deal and the UK wants to discuss trade or other subjects, we will put the same subjects back on the table."
Mr Barnier told the European Parliament Committee on Foreign Relations: "We are not yet at the end of the process. President (Jean-Claude) Juncker has said our patience has reached an end, but I think we are a little bit from the end. We still have a little bit of patience.
"We hope that the British Parliament will do what it can to ratify this agreement.
"Perhaps they may ask us to amend the Political Declaration, perhaps improvements can be made. This can be done over a period of days or weeks, this is possible, we can be more ambitious in all of the areas of this Political Declaration.
"But I really hope that we won't just abandon all the work that has been done, because for a withdrawal to take place in an orderly manner, this is the only possibility."
The Committee's chairman, German MEP David McAllister, told Mr Barnier that the message to Westminster was "keep calm and carry on indicative voting".
Mr McAllister added, his tongue apparently in his cheek: "We are following procedures in the House of Commons with utter admiration."
The vice-president of the European Parliament has said "it does look like" a no-deal Brexit is "nearly inevitable".
Mairead McGuinness was commenting on a tweet sent by the European Parliament's Brexit coordinator, Guy Verhofstadt, in which he said that after Monday's Commons votes "a hard #Brexit becomes nearly inevitable".
"It does look like that, given what happened yesterday, and the fact that the Withdrawal Agreement which is on the table for ratification has not been ratified by the House of Commons," she told BBC Breakfast.
The House of Commons again votes against all options. A hard #Brexit becomes nearly inevitable. On Wednesday, the U.K. has a last chance to break the deadlock or face the abyss. https://t.co/iixDhr5t6N— Guy Verhofstadt (@guyverhofstadt) April 1, 2019
"When you look at the timelines there is concern here in the European Union that the failure of the House of Commons to rally around any particular option leaves us with that thought: that there is this lurching, perhaps by accident, towards a no-deal scenario."
She added that, while a no-deal Brexit was not the desire of the EU, "these things can happen by accident rather than design".