Theresa May faced new pressure from Tory backbenchers pushing for a hard Brexit this weekend, amid reports that European leaders have come to a 27-nation consensus that the UK must be forced into a full exit in order to counter the rise of populist movements on the continent.

A group of 60 Tory MPs including seven ex-cabinet ministers have demanded the Prime Minister pulls Britain out of the single market and customs union amid fears her Brexit stance is being softened by pro-EU figures in her cabinet. The group, which includes heavyweight Brexiteers Michael Gove, Iain Duncan Smith, John Whittingdale and Theresa Villiers, made their call in the Sunday Telegraph, saying Britain should “untie [itself] from EU shackles and freely embrace the rest of the world”. It comes amid reports that the 27 other EU member states – who will all have to agree on the terms under which Britain will leave the bloc – are in agreement that the UK will have to be forced into a hard Brexit to discourage other countries to follow suit.

Existential danger “If you British are not prepared to compromise on free movement, the only way to deal with Brexit is hard Brexit” EU diplomat Senior EU officials giving Britain favourable terms of exit could represent an existential danger to the EU, since it would encourage similar demands from other countries with significant Eurosceptic movements.

One top EU diplomat told the Observer: “If you British are not prepared to compromise on free movement, the only way to deal with Brexit is hard Brexit. Otherwise we would be seen to be giving in to a country that is leaving. That would be fatal.” Ukip interim leader Nigel Farage has warned it could be “game over for the EU” if Marine Le Pen, leader of the anti-immigrant, anti-EU Front National, wins France’s presidential election in spring. Deeply divided Ms May’s cabinet is deeply divided over whether Britain should pull out of the EU single market, a tariff-free trade bloc, and customs union, which allows goods to cross borders without customs checks. The Prime Minister has previously said she would try to restrict freedom of movement between the UK and EU – a policy which is incompatible with membership of the single market.

Pressure from Eurosceptic backbenchers follows calls on Saturday by some Tory MPs for the government to drop its attempt to appeal against having to hold a parliamentary vote on triggering Article 50, which starts the formal process of withdrawing from the EU. There are concerns that the waiting time – a judgment is not due until January – is an unnecessary delay.