Pro-EU Conservatives have condemned Theresa May's Brexit strategy, urging her to stand up to party “zealots” to avoid huge damage to Britain.

The 30-strong Conservative Group for Europe (CGE) accuses the Prime Minister of appearing to be “asking for the wrong things, in the wrong way and on the wrong timescale”.

Its devastating analysis – published just hours before two crucial Commons votes on the Article 50 Bill – protests that Ms May has:

* Adopted an “intimidatory stance towards critics” who oppose her “extreme” Brexit - which will prolong the nation’s divisions and alienate business groups.

* Provided “no clues” about a future partnership with the EU – accusing her putting “hostility towards the EU” ahead of the national interest.

* Wrongly said it is “impossible for Britain to retain single market membership whilst limiting freedom of movement” – when a “grand bargain” with the EU might still be possible.

* Allowed an “ideological hostility to the European Court of Justice” to drive her negotiating strategy.

* Refused to recognise that any post-Brexit free trade agreement with the EU “will fall far short of replicating the benefits of the single market, especially in services” – making a “significant transitional period” essential.

* Risked fuelling momentum for Scottish independence while undermining the Good Friday Agreement in Northern Ireland.

* Weakened ties with the EU despite “the volatile nature of the new US Administration and the aggressive behaviour of Russia”.

The paper warns: “The risks are high that the outcome of the exit negotiations will cause significant damage to the political and economic interests of both Britain and the EU, blighting relations for a generation.”

The group’s president is Brexit rebel Ken Clarke and the group boasts other MPs including Nicholas Soames, Caroline Spelman, Neil Carmichael, Robert Buckland and Robert Walter.

Other supporters include Sir John Major, the former Prime Minister, and former Conservative Cabinet ministers Lord Heseltine, Lord Hurd, Lord Carrington and Lord Patten.

The report’s author, CGE vice-chairman Edward Bickham, mocked Ms May's insistence that “no deal” with the EU would be better than a “bad deal”.

“Theoretically she is right, but only if the 'bad deal' is in compulsory slaughter of the first-born territory,” Mr Bickham said.

“We are fooling ourselves - and the Government would be fooling the British people - if we fail to understand that a default to trading with out biggest (and currently most closely integrated) trading partners on the basis of WTO rules would be profoundly damaging.”

Mr Bickham urged the Prime Minister to “change direction to deliver a better Brexit, adding: “That will involve disappointing the Brexit zealots.”

The comments were endorsed by Mr Carmichael, who said: “This publication is a powerful contribution to the necessary debate following the referendum decision as the period of negotiation under Article 50 begins.”

However, despite the strong language, Commons Tory revolts on both securing a ‘meaningful vote’ on the final Brexit deal and guaranteeing the rights of EU citizens appeared to be melting away.