Tony Blair today declared he is in an 'unholy alliance' with Boris Johnson to try to thwart Theresa May's Brexit plan getting through Parliament.

The former Prime Minister lashed the EU withdrawal deal which has been thrashed out - branding it the 'worst of both worlds'.

And he urged MPs to rise up, revolt against the deal and demand a second referendum instead.

The ex Labour leader - a leading Remainer - also tore into Jeremy Corbyn for his 'abject refusal' to lead the UK 'out of the Brexit nightmare'.

He took aim at Mrs May's plan in a speech in central London just as the PM was holding a crunch Cabinet meeting where the fate of her deal - and premiership - hang in the balance.

Mr Blair told an audience at the British Academy: 'Remainers like me, leavers like Boris Johnson, are now in unholy alliance.

'We agree this is a pointless Brexit, in name only, which is not the best of a bad job, but the worst of both worlds.'

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Tony Blair (pictured at the Royal Academy in London today) declared he is in an 'unholy alliance' with Boris Johnson to try to thwart Theresa May's Brexit plan getting through Parliament

Boris Johnson (pictured today in Westminster) has torn into the PM's Brexit deal and yesterday called on Cabinet ministers to resign over it

Mr Johnson has torn into the PM's Brexit deal and yesterday called on Cabinet ministers to resign over it.

The former foreign secretary urged ministers to 'live up to their responsibilities' by blocking the agreement from going forward.

Delivering the latest in a string of speeches on Brexit in recent weeks, Mr Blair stepped up his call for another referendum, insisting it is the only way to reunite a deeply divided country.

He said: 'There is only one way of ending the argument and reuniting the country. The only route to unity is clarity. And the only route to clarify is through the people.

'Parliament must ask the British people to resolve the matter, to reconsider, to clarify their mandate, to do so in a vote which is accepted by all sides as conclusive, to give each side the chance to remake their case on the basis not on claim and counter claim, but of the experience of the past 30 months.'

He savaged Mrs May's Brexit deal, saying it amounted to 'capitulation' to the EU.

He said: 'Nothing can disguise the nature of the deal she has chosen, if reports of it are true. This deal isn't a compromise, it's a capitulation.

'The withdrawal agreement will keep us tied to EU trade policy until there is an end established by 'joint consent' - in other words, the EU has a veto.

'It is coated in heavy fudge, but that is the inedible biscuit beneath the coating.'

Mrs May is facing a barrage of attacks from all sides after details of her Brexit deal began leaking last night.

She is braced for a possible wave of Cabinet resignations today after a crunch meeting with her senior ministers where they will decide if they can back the deal or will walk.

Theresa May arrived back at Downing Street for the Cabinet meeting today after delivering an impassioned defence of the package at PMQs

Aid Secretary Penny Mordaunt was summoned to Downing Street for pre-Cabinet talks this morning, amid rumours she is considering quitting. And she was one of the first to arrive for the Cabinet meeting this afternoon

Boris Johnson highlighted the remarks by Ms Weyand as he urged ministers to 'stop this deal'

Aid Secretary Penny Mordaunt, one of those closest to the edge, was among the first arrivals for the meeting this afternoon.

And Scottish Secretary David Mundell has emerged as a potential risk after he signed a letter warning the PM against giving away fishing rights as part of the agreement.

Brexiteers are furious at backstop plans which will keep the whole of the UK tied to the EU customs union and many single market rules.

They warn this will leave the country a 'slave' to the EU - having to swallow its rules while having no say.

While the DUP - who are propping the Tories up in No10 - are fuming at reports Northern Ireland will have more regulatory checks than the rest of the UK.

They warn this could drive a wedge through the UK and have said they could pull their support for the PM over the plans.

While Brexiteers are hammering the deal on one side of the argument, Remainers are stepping up their attempts to thwart it.

They believe they have the PM on the ropes and can force a second referendum - paving the way to keep the UK in the Brussels bloc.