Boris Johnson will try to find a legal loophole to force through Brexit on October 31, senior cabinet ministers have suggested.

Foreign Secretary Dominic Raab said the government would “test to the limit” laws passed by parliament last week which aim to stop Britain leaving the EU with no deal on Halloween.

He insisted the government would “behave lawfully” but said ministers would “look very carefully, legally” at what the legislation “requires and doesn’t require”.

Chancellor Sajid Javid also stressed there are “a lot of days” to react to the anti-no deal law between now and October 19, at which point the government will be legally required to delay Brexit if it cannot get MPs’ approval for leaving with no deal, or a renegotiated agreement.

Labour branded the position “extraordinary and elitist” and likened the prime minister to a “tinpot dictator”.

It comes with Johnson appearing cornered after saying he would rather be “dead in a ditch” than delay Brexit beyond October 31. His plan B to hold a snap election to win a majority and mandate for a Halloween Brexit, deal or no deal, has also been rejected by MPs.

Adding to Johnson’s woes, Amber Rudd last night dramatically quit the cabinet and gave up the the party whip to sit with 21 Tory rebels who backed the cross-party anti-no deal legislation, complaining that the government does not have a detailed plan to get a new deal.

Raab insisted there has been progress in negotiations, but suggested the government would fight to keep no deal on the table and would be prepared to take the battle to court if required, dismissing suggestions the PM could face prison if he refuses to delay Brexit.

He told Sky News’s Ridge on Sunday: “The key thing with an extension is it requires agreement on both sides.

“I think it is very difficult for the legislation to micromanage in detail how that conversation will go.

“We will adhere to the law, but we will also, because this is such a bad piece of legislation, the surrender bill Jeremy Corbyn backed, we also want to test to the limit what it does actually lawfully require.

“We will look very carefully at the implications and our interpretation of it.

“Across the board we will look very carefully, legally, at what it requires and what it doesn’t require.

“I think that’s not only the lawful thing to do, I think it’s also the responsible thing to do.”

Javid told the BBC’s Andrew Marr to “wait and see” when questioned about the anti-no deal law.

He said: “We will not change our policy, we will have to wait and see.

“We will be consistent with obeying the law but also sticking to our policy, and you will have to wait and see what happens because there is a lot of days between now and October 19.”

Justice Secretary Robert Buckland meanwhile suggested he had received reassurances that Johnson would obey the law.

Meanwhile, Raab said he was “really sorry” to see the resignation of Rudd, who has been replaced as work and pensions secretary by Therese Coffey.

He said: “I’m really sorry to see Amber step down, I like her, I respect her.

“We became MPs at the same time in 2010, but I think in fairness when she took the cabinet role everyone was asked ‘do you accept and can you sign up and will you support the prime minister’s plan to leave by the end of October preferably with a deal, but if not come what may’ and we all accepted that.

“I think the prime minister was right to restore some discipline and I think he’s right to expect it from his top team.”

He added: “It’s been a rough week, but the reality is the prime minister is sticking to his guns on what he said to get us out of this rut that we’re in.”

Shadow attorney general and Labour peer Baroness Chakrabarti branded the government’s position on the anti-no deal law “extraordinary”.

She told Ridge: “I think the position is irresponsible and elitist, the idea there’s one law for Boris Johnson and his mates and another law for everyone else, it’s appalling.”

She added: “Every tinpot dictator on the planet throughout history has used the excuse of having the people on their side to break the law to shut down parliament and all the rest of it, it’s absolutely extraordinary and I think it’s very un-British, as was the purge of the 21 MPs, who are Conservatives, they’re not secret Corbynistas.”

She went on: “The legislation is crystal clear, if you don’t have a deal in the next few weeks you have to apply for the extension, it’s a duty that’s laid in the legislation on the prime minister personally.”

Shadow chancellor John McDonnell said Johnson could not be trusted to obey the law.

He continued: “I think we’re in an extremely serious constitutional position.

“We don’t believe that we can pin him down and I don’t trust him an inch, and I don’t think anyone does. We’ve got a prime minister who has said he would not abide by the law.

“We’re in a situation where no-one can trust while he’s in place what could happen.”