Senior Labour backbenchers have begun talks with Liberal Democrat, Green and Ukip MPs to set up a new cross party campaign to bring about proportional representation (PR) in general elections.

The former shadow Business Secretary Chuka Umunna, along with the former shadow Transport Minister Jonathan Reynolds, called for their party to ditch its opposition to PR and align with other parties to support electoral reform.

They have set up an All Party Group in Parliament to push for the reform, which they said would help to restore the public’s trust in politics.

“I think Labour has missed an opportunity by failing to support proportional representation in the past,” Mr Umunna told The Independent. “The first past the post system is clearly unsustainable when you have a multi-party system where millions of votes are effectively not counted.

“You only need to look at Scotland, where the SNP got 50 per cent of the vote but 95 per cent of the seats.”

Under the plan, the group would push for Labour and other opposition parties to go into the next election pledging to implement the Additional Member System that is used for Scottish Parliamentary elections. Under this system there would still be constituency MPs but these would be “topped up” by party lists to make the House of Commons representative of the national vote. Commenting on the new group, Mr Reynolds said their proposed system would “keep the best bits of what we have now, such as the constituency link for MPs”, but would better represent how people vote.