THE author of Labour’s 2017 General Election manifesto has accused the party’s Scottish branch of attempting to “sabotage” the campaign.

Andrew Fisher, who was Labour’s executive director of policy under Jeremy Corbyn, claimed an internal probe had found that the manifesto was leaked to the right-wing press before it was officially published.

The 2017 election saw Theresa May’s Conservatives lose the narrow majority David Cameron had won in 2015 while Labour gained 30 seats.

Corbyn’s Labour made manifesto commitments to nationalise the railways, energy, and postal service and to introduce a pay cap on firms given government contracts.

The National: Former Labour leader Jeremy Corbyn launching the manifesto which had been leaked to the pressFormer Labour leader Jeremy Corbyn launching the manifesto which had been leaked to the press

Fisher, who led the writing of the manifesto, said its leaking to the press before the official release was something which “had never happened before in British electoral history”.

He wrote on Twitter: “The Daily Mirror and Daily Telegraph had the manifesto, and were going to publish it.

“I had been working over 100 hours a week, non-stop writing, editing and negotiating – alongside a brilliant team doing similarly “I was gutted and angry, wondering ‘HOW?’”

Fisher said that a probe into the source of the leak eventually turned up just two possibilities, that either Scottish or Welsh Labour had given it to the press.

“I was later told by the senior Labour staffer who investigated that the leak had come from the Scottish Labour office,” he wrote.

“The leak was an attempt to sabotage the party, and the headlines the next morning reflected that …”

Fisher shared images of the front pages of the Daily Mail and the Telegraph, which both carried the story along with similar headlines claiming Corbyn aimed to “drag [the UK] back to the 1970s”.

He added: “As acts of sabotage go, it probably backfired more than any other in political history. It generated massive coverage and discussion of radical and interesting policy.”

Scottish Labour was led by Kezia Dugdale at the time of the leak.

The party has been approached for comment.