The European Parliament will block the withdrawal agreement if British MPs try to amend it, the body’s Brexit chief has warned ahead of a series of key votes in Westminster.

Guy Verhofstadt told The Independent that the EU’s legislature, which has to approve any deal, would not consent to a “watered down” agreement and that the controversial Irish backstop could not be ditched.

His intervention comes as MPs look set to consider a series of amendments tabled by Brexiteers instructing the government to scrap the bits of the deal they do not like.

Eurosceptic MPs have also tried to unilaterally amend the withdrawal agreement itself during the ratification process – an approach rebels are expected to repeat when the treaty soon returns to the Commons for a second vote.

But the intervention by the European Parliament’s high-profile Brexit coordinator shows the pressure the EU side is under not to budge on UK demands from MEPs as well as its member states.

Brexit: the deciders Show all 8 1 /8 Brexit: the deciders Brexit: the deciders European Union's chief Brexit negotiator, Michel Barnier Getty Brexit: the deciders French President Emmanuel Macron Getty Brexit: the deciders German Chancellor Angela Merkel Reuters Brexit: the deciders Commission President Jean-Claude Juncker EPA Brexit: the deciders The European Parliament's chief Brexit negotiator Guy Verhofstadt Getty Brexit: the deciders Britain's Prime Minister Theresa May Getty Images Brexit: the deciders Britain's Chancellor of the Exchequer, Philip Hammond PA Brexit: the deciders After the first and second appointed Brexit secretaries resigned (David Davis and Dominic Raab respectively), Stephen Barclay is currently heading up the position PA

“The European Parliament will not give its consent to a watered down Withdrawal Agreement,” Mr Verhofstadt told The Independent.

“The deal we have is fair and cannot be re-negotiated. The backstop is needed because of UK red – lines and was crafted by the UK and the EU to secure the Good Friday Agreement.

“We remain open to positive changes regarding the future relationship and it is time for a more consensual cross- party approach to deliver this.”

Last week the European Parliament’s Brexit steering group, which Mr Verhofstadt chairs, agreed that “without such an ‘all-weather’ backstop-insurance, the European Parliament will not give its consent to the Withdrawal Agreement”.

One amendment which looks set to be considered by MPs is the so-called Brady Amendment, tabled by the chair of the Tory MPs’ 1922 Committee Graham Brady.

The plan, due to be voted on on Tuesday evening, says the backstop should be “replaced with alternative arrangements to avoid a hard border”. The Government has indicated it will whip its MPs to back the proposal, though it is not clear whether it will pass.

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Another plan, known as the Malthouse Compromise after the Tory minister Kit Malthouse, would see the backstop dropped and the transition extended in exchange for the UK paying some of the financial settlement it owes Brussels.

EU officials speaking behind the scenes have already rejected this idea, stating that they would not agree to the removal of the backstop. One diplomat described it as “nonsense” while another said the suggestion was “funny and tragic” and had “zero chance” of working.

Brexiteer Tory MP Iain Duncan Smith meanwhile said on Tuesday morning that the plan represented “the best hope that we’ve got”.

Other MPs have also tabled their own amendments. Most notable among these is the Cooper amendment, tabled by Labour MP Yvette Cooper. This would instruct the Government to extend Article 50 to the end of 2019 if the prime minister does not manage to agree to a deal by late February.

Today’s amendments, which will be voted on subject to the Speaker John Bercow selecting them for debate, are to Theresa May’s statement about the defeat of her Brexit deal. The statement to MPs was required by the Withdrawal Act in the event that the plan was rejected by the Commons.