Nigel Farage has said that the Brexit vote could be overturned if Leave campaigners do not step up efforts to fight for their cause.

The former Ukip leader said he was increasingly worried that pro-EU campaigners were dominating the argument, while Leave supporters had just "closed the doors" after securing victory in the 2016 referendum.

Mr Farage, who is seen by many as an architect of Brexit, also reignited the debate this week when he said a second referendum was necessary to stop the "whingeing and whining" of prominent Remain backers, who have failed to accept the result of the vote.

A snap poll conducted after his intervention found 55 per cent would opt to remain in the EU and 45 per cent to leave if there was another vote. The original vote was 52 per cent to 48 per cent in favour of Brexit.

In an interview with The Observer, Mr Farage said: "The Remain side are making all the running.

"They have a majority in Parliament and unless we get ourselves organised we could lose the historic victory that was Brexit."

In a rallying cry to Eurosceptics, Mr Farage signalled the need to hold the Government's feet to fire to ensure it does not offer too many concessions to Brussels.

He said: “I think the Leave side is in danger of not even making the argument.

"The Leave groups need to regather and regroup, because Remain is making all the arguments. After we won the referendum, we closed the doors and stopped making the argument.”

It comes as Theresa May's flagship Brexit legislation was set to return to the Commons, where it faces a number of challenges from opposition MPs before it heads to the Lords for scrutiny in the coming weeks

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

SNP, Green, Liberal Democrat and Plaid Cymru MPs have tabled an amendment to the EU (Withdrawal) Bill that would stop ministers from using sweeping powers to take the UK out of the single market and the customs union after Brexit.