Avramopoulos also said the bloc's no-deal contingency plans on security were driven by "goodwill", stressing the bloc would want to continue cooperating with Britain closely, including on sharing intelligence.
But EU diplomats and officials said on Monday the focus of their session would instead be on the EU's own Brexit preparations, including for a "no-deal" outcome. However, some cabinet Brexiteers have suggested that they would resign over this.
"My estimate is that there are at least 40 colleagues who are not going to accept a "half in, half out" Chequers deal or indeed a backstop that leaves us in the internal market and the customs union".
She told reporters: "There can not be barriers to trade in the United Kingdom internal market".
At his latest appearance in parliament, where divisions over how to leave the European Union were on display, Raab moved to downplay one of the thorniest parts of the talks - a so-called backstop arrangement to prevent the return of a hard border between the British province of Northern Ireland and European Union member Ireland.
EU Brexit chief negotiator Michel Barnier was set to present the document, known as the "political declaration", to the weekly meeting of the EU's 28 commissioners.
"The Prime Minister understands that position and I expect her to respect that position".
However, the European Union says that means there must be some checks on goods coming into Northern Ireland in order to prevent those that do not meet European Union standards from going across in the Republic of Ireland and then reaching the continent.
But on actually getting a deal, he said: "We've always been clear we would aim for the October council but there would be leeway, that it might slip into November".
Mrs May told the regular weekly Cabinet meeting at 10 Downing Street that talks to finalise a withdrawal deal were continuing "on an intensive basis".
But Foster refused to consider such a compromise on Tuesday, saying: "What we said to Barnier is checks of themselves are symptomatic of something different, so we only need checks if Northern Ireland is following a different regulatory regime to the rest of the UK".
The US-based organisation said a "no-deal" departure from the EU could lead to fragmentation in European money markets, meaning finance cannot flow around the system so efficiently.
She added that they should also remember that Parliament gave the British people the decision over Brexit and following the 2016 referendum result "it is our duty to ensure that we leave".
If lawmakers reject a deal, May could fall and Britain would face leaving the European Union without an agreement, a move investors and company chiefs say would weaken the West, panic financial markets and block the arteries of trade.
The EU's proposed solution - to keep Northern Ireland inside the bloc's single market and customs union after the rest of the United Kingdom leaves - is fiercely opposed by the Democratic Unionist Party, a pro-British Northern Ireland party that props up May's minority government.
Earlier, amid speculation possible of ministerial resignations, Work and Pensions Secretary Esther McVey, who was not at the meeting, pointedly refused to endorse the Prime Minister's Chequers blueprint for Brexit.