A no-deal Brexit is a “very distinct possibility” and European Union citizens and businesses must be ready for Britain's departure on October 31, the bloc's executive said on Tuesday.

In London, British lawmakers were trying to stop Prime Minister Boris Johnson from pursuing what they cast as a calamitous no-deal Brexit, amid speculation that the government could call a snap election on October 14.

“Our working assumption is that there will be Brexit on October 31,” European Commission spokeswoman Mina Andreeva said.

Asked whether a no-deal exit was now the most likely scenario, she said: “I would say it is a very distinct possibility, which is precisely why we launch this final call to be prepared in case a no-deal Brexit occurs.”

She added: “The best outcome would be a Brexit on the basis of the negotiated withdrawal agreement.”

The deeply divided British parliament has rejected the deal London had negotiated with the bloc three times and Johnson has said the so-called Irish backstop must be removed from the agreement to ensure ratification.

The backstop is meant to uphold the invisible border between EU-member Ireland and the British province of Northern Ireland after the United Kingdom leaves the EU. Brexit supporters in London and unionists in Northern Ireland fear it will tie the UK to the EU's trading rules indefinitely.

Diplomatic sources dealing with Brexit in Brussels for the EU member states said they were informed by the Commission that British and EU negotiators would meet every Wednesday and Friday for talks.

Andreeva said while there had been an acceleration in talks since Johnson met EU leaders — German Chancellor Angela Merkel and French President Emmanuel Macron at the G7 summit in Biarritz last month — there was no breakthrough on substance.

“I cannot report any concrete proposals being made,” she said of the EU's demand that London presents detailed and operational ideas on how the backstop could be replaced from day one after Brexit.

EU Brexit negotiator Michel Barnier is due to brief the 27 national ambassadors on Wednesday and the Commission will present an updated note on the bloc's contingency preparations for a no-deal divorce.

It will include a possibility to grant emergency aid to businesses and countries affected through an EU Solidarity Fund — normally reserved for natural disasters — and another fund targeting communities suffering from job losses stemming from changes to trade patterns in a globalised world.

Irish border conundrum

On Tuesday, EU diplomats were told by the Commission — negotiating Brexit with London on behalf of the 27 remaining member states — that Johnson's government kept delaying delivery of its plans for alternatives to the Irish backstop.

“There is a degree of frustration in the Commission. Each time they ask for detail on these alternative arrangements they hear 'We will get to it next week',” one diplomat said.

“Nothing concrete has been tabled and it looks very unlikely that the British side would come up with anything concrete. They are running down the clock.”

Diplomatic sources said the Commission was concerned Johnson's government was only considering avoiding checks at the Irish border — the only land frontier between the EU and UK after Brexit — but was not looking to uphold frictionless cooperation in trade and other areas between the two entities.

“London doesn't seem to be treating the island of Ireland as a single economic area anymore,” said another diplomat.

The EU doubts London would be able to find acceptable ways to manage the Irish border after Brexit after three years of negotiations that failed to produce better solutions.