Jeremy Corbyn has refused to rule out seeking to revoke article 50 to prevent Britain from sliding into a no-deal Brexit, as senior EU officials privately talked up the possibility before a crucial summit in Brussels.

Speaking outside the European commission headquarters in Brussels, the Labour leader insisted his focus “at the moment” remained on trying to push the prime minister into a soft Brexit.

“These are hypotheticals,” Corbyn said in response to reporters’ questions over cancelling Brexit. “So far as we’re concerned we think there’s an urgency in constructing a majority for an agreeable solution and that’s what we’re concentrating on at the moment.”

Corbyn was holding talks with Michel Barnier, the EU’s chief negotiator, and Martin Selmayr, the European commission’s secretary general, before Theresa May’s arrival at a leaders’ summit in Brussels on Thursday. Labour subsequently issued a statement saying cancelling Brexit was not its policy.

A spokesperson said: “As we have always said, we respect the result of the referendum and will do whatever is necessary to prevent a no-deal outcome. We do not believe that revoking article 50 is in any way necessary.”

Selmayr privately suggested this week that the UK would end up seeking to revoke article 50 if the alternative was a no-deal Brexit. However, Corbyn made clear his preference would be for the prime minister to engage with his vision of a softer Brexit and permanent customs union.

Q&A Might the UK still take part in European parliamentary elections? Show Hide At the moment there seems to be three likely Brexit outcomes: a no deal departure on 12 April, a departure on 22 May with Theresa May's deal, or a lengthy extension to the process. The EU is only likely to grant a long extension if there is a significant change in the UK's position. For example, calling a second referendum, holding a general election, or asking the EU to renegotiate the political declaration that accompanies the withdrawal agreement. If the EU were to grant an extension beyond 22 May, the UK would be required to hold and participate in the European Parliamentary elections, which would take place on Thursday 23 May.

“We think that what we’re proposing can be achieved in the British parliament; we do believe we can construct a majority that will prevent the crashing out and all the chaos that will come from crashing out and that’s what we’re absolutely focused on,” he said.

Corbyn has called for cross-party consensus to achieve that but drew criticism for walking out of a meeting in Downing Street earlier this week because Chuka Umunna, who quit Labour to form the Independent Group, was present.

Asked why people should believe that he was committed to cross-party cooperation in the light of what happened, he replied: “There was a confusion over that meeting. I had a separate and very extensive discussion with the prime minister later on. I’m also arranging to meet the prime minister next week, on a one-to-one basis as leader of the opposition. I have met with the leaders of all the other parties in parliament in my office this week, and Keir [Starmer] has also met with delegations from all across the House of Commons. We have done a great deal.”

Corbyn’s refusal to rule out revocation of article 50 will cheer many of those in Labour campaigning for the UK to have the chance to remain in the EU. But it would also be divisive, as some Labour MPs with leave-voting seats are concerned about the electoral consequences of failing to back Brexit.

Nicola Sturgeon, the first minister of Scotland and the SNP leader, gave her support to revocation on Thursday, saying that SNP MPs would never accept May’s framing of the argument as a “choice between her deal and no-deal”.

“Just because she’s not willing to contemplate the alternatives, doesn’t mean there aren’t any alternatives,” she said. “One of those alternatives undoubtedly is the revocation of article 50 and if all else fails by this time next week, that is exactly my view of what MPs should do.”

Asked about the possibility, May’s deputy official spokeswoman said there was no chance of the prime minister supporting such as course of action. She said the prime minister had said “about 12,000 times” that she would not be prepared to revoke article 50.