Boris Johnson has no intention of renegotiating the withdrawal agreement and a no-deal Brexit is his “central scenario”, European diplomats have been told, amid hardening evidence in Westminster that the government is expecting to crash out of the EU.

Brussels diplomats briefed after a meeting between the prime minister’s chief envoy and senior EU figures in Brussels said that Britain’s refusal to compromise was understood to have been clear to those attending.

Instead David Frost, the government’s new chief Europe adviser, is said to have sought discussions on how negotiations could be reset after the UK crashes out on 31 October.

“It was clear UK does not have another plan,” a senior EU diplomat said of the meetings with Frost. “No intention to negotiate, which would require a plan. A no deal now appears to be the UK government’s central scenario.”

The disclosure came as No 10 insisted the government was “ready to negotiate in good faith” but made clear that Johnson would only agree to a deal without what he refers to as the “undemocratic backstop” – the mechanism to prevent a hard border on the island of Ireland that could keep the UK in a customs union. The EU has repeatedly said the backstop is not up for negotiation.

The UK’s failure to provide any proposals on how to deal with the controversial Irish backstop was felt to be significant by EU officials who spoke to the Guardian.

Frost was said to have told the officials that a technological solution to the Irish border was the UK’s preferred option before admitting that “it would not be ready now for Brexit”.

“Even if EU gave up the backstop there is no alternative,” a diplomat concluded of the discussion.

“That message has now gone loud and clear to capitals, it was useful to hear it from horse’s mouth,” the EU source said. “Reality is sinking in.”

With no new UK-EU talks scheduled, there were meanwhile signs in Westminster that Johnson’s government was readying itself for a no-deal Brexit and preparing to do battle with Tory MPs who have said they will join with opposition parties to prevent that outcome.

The prime minister’s senior adviser, Dominic Cummings, instructed special advisers across the government to keep on top of preparations for a no deal Brexit early on Monday morning and attacked Philip Hammond, the former chancellor, for failing to get the country ready.

Over the weekend, it became clear he believes that Johnson could simply refuse to resign in the event of losing a no-confidence motion and schedule an general election for November – after leaving the EU at the end of October.

Johnson said on Monday that an election was the “last thing” he wanted. But his official spokesman stressed at his regular briefing for journalists that Brexit would take place on 31 October “whatever the circumstances”, even if parliament has voted against a no-deal departure or passed a confidence motion against the prime minister necessitating an election.

Conservative rebels plotting against a no-deal Brexit are already considering how to thwart No 10, believing an alternative government could potentially be created with a majority to challenge Johnson if he loses a confidence vote.

Corbyn indicated on Monday that he may be prepared to bring a no-confidence vote in the government very soon after parliament returns from its summer break in September.

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“We will do everything to stop no deal, including a no-confidence vote at the appropriate very early time to do it,” he said on a visit to flood-stricken Whaley Bridge in Derbyshire. “The prime minister seems to be trying to slip no deal through, slip past parliament and slip past the British people.

“Sorry, no deal will be really serious. Serious for food prices, for medical supplies, for trade, for investment, and drive us straight into the hands of the sort of trade deal that Donald Trump wants to do with Boris Johnson.

“I’m sorry, it’s not on, it’s not acceptable. We will do everything we can to block it.”

Several Conservative MPs, including Hammond, have indicated they could vote with Labour to bring Johnson down if he is set on a no-deal Brexit. Friends of Hammond also hit back at Cummings on Monday, saying it was “simply untrue” that the Treasury had failed to prepare.

“The bigger question is why is Dominic Cummings, the de facto deputy PM, so keen to spend yet more taxpayers’ money on something that his boss insists has only a one in a million chance of happening?” one Hammond ally said.

EU officials increasingly believe the UK is heading for a no-deal exit after their meetings with Frost, who replaced Theresa May’s chief negotiator, Olly Robbins. Last week, Frost met Clara Martínez Alberola, the head of cabinet for the European commission president, Jean-Claude Juncker; Stéphanie Riso, a senior official in Michel Barnier’s negotiations taskforce, who was a key player in drafting the terms of the backstop, and Ilze Juhansone, the deputy secretary general at the commission.

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The demand over the weekend by the Brexit secretary, Stephen Barclay, that Barnier seek a new negotiating mandate from the EU’s leaders to allow fresh talks was seen as mere “noise”.

Diplomats said the message was seen as “confrontational – unhelpful” but that more in that vein was expected at a meeting of the G7 in Biarritz, when Johnson will meet Juncker.

A spokeswoman for the European commission said the impact of the UK crashing out would be proportionally heavier on the British side of the Channel.

The spokeswoman added: “For a negotiation to be successful it takes two to tango. If the music and the rhythm is not right then … you have no dance.

“But that doesn’t mean that it was a failure. I think both sides negotiated with the very best intentions and very best efforts. The outcome on the table is the best deal possible and I don’t think there is any fault or blame to be looked for in this.”

A UK government spokesman said: “We are ready to negotiate in good faith an alternative to the anti-democratic backstop.

“There is abundant scope to find the technological solutions necessary – and these solutions can and will be found, in the context of the free trade agreement that we will negotiate with the EU after 31 October.”

The spokesman added: “The prime minister wants to meet EU leaders and negotiate a new deal – one that abolishes the anti-democratic backstop.

“We will throw ourselves into the negotiations with the greatest energy and the spirit of friendship. The fact is the withdrawal agreement has been rejected by parliament three times and will not pass in its current form so – if the EU wants a deal – it needs to change its stance. Until then, we will continue to prepare to leave the EU on 31 October.”