Labour will table an amendment to any Article 50 legislation, says Jeremy Corbyn

‘We want those to be part of the negotiations but we are respecting the result of the referendum. It’s not the one we wanted – it’s the one we’ve got’

The Labour leader made clear it was not an attempt to overturn the result of the referendum (PA)

Jeremy Corbyn has revealed Labour will seek an official amendment to any Article 50 legislation, if Theresa May is forced to seek approval to trigger the mechanism in the Commons.

His comments come as Government lawyers prepare to present their case at the Supreme Court on Monday to trigger Article 50 – the untested protocol for a member state leaving the EU – without an Act of Parliament. Some ministers are privately expecting Downing Street to lose the challenge.

Speaking to Sky News after a speech to the party of European Socialists in Prague, the Labour leader said: “When the Article 50 debate comes up we will put forward an amendment to it, which will be on the issues I’ve just said about market access and protections.”

But the Labour leader reiterated his party would not seek to overturn the decision by the British people to leave the EU at the referendum in June. “We want those to be part of the negotiations but we are respecting the result of the referendum,” he said. ”It’s not the one we wanted – it’s the one we’ve got.”

Mr Corbyn, who is attempting to ensure Britain maintains access to Europe’s markets, workers’ rights and environmental protection measures, added: “You can't say to be people: ‘You vote, you take the decision. Sorry, you’ve made the wrong decision. You’ve got to take it again’.

“Two thirds of Labour voters voted to remain. There isn’t a blank cheque to the Government – it’s up to us, to Parliament, to hold the Government to account. That is exactly what we are doing.

“Article 50 will still be invoked. We are not going to block it. We don’t think that's right to do that. But I do think there will be a considerable body of MPs on both sides which does require an amendment that supports a trade agreement with Europe in the future.”

In the event of the Prime Minister losing the Supreme Court case in January, it has been reported the Government is already in the process of drafting a bill in just two or three lines – in an attempt to make it difficult for amendments to succeed.

Mr Corbyn added: “There are those in the Tory party who want us to sever all connection with Europe, reduce corporate taxation, set up some kind of bargain basement trade agreement with the USA.

“The result would be a reduction in wages, reduction in public expenditure and ultimately a big reduction in living standards across Britain.”

His announcement comes after he used a speech to suggest Europe’s centre-left parties must reject the establishment – or watch the populist far-right win across the continent. In a speech to Labour’s European sister parties in Prague, the Labour leader warned that the populist right had correctly identified problems with the prevailing economic model.

But he argued the solutions of those anti-immigrant, anti-EU, and anti-Islam parties were only “toxic dead ends” that would not solve people’s problems. Mr Corbyn’s comments come a day before Austria votes in a rerun of its presidential election – in which a far-right Norbert Hofer could be on the verge of victory.

A Conservative spokesman said: “Yet again, Labour have shown they want to frustrate the will of the British people by slowing down the process of leaving the European Union and trying to tie the Government’s hands in a negotiation.

“Labour are utterly out of touch with the values of working people across our country.

“Only the Conservatives can be trusted to respect the outcome of the referendum and make a success of Brexit.”