A pro-Jeremy Corbyn campaign group will try to force the Labour Party to adopt a four-day working week as official policy ahead of the next general election.

Momentum will use its 40,000-strong activist base to campaign in the run up to Labour’s annual party conference in September to push through “radical and transformational” pledges.

Those pledges will also include a much tougher position on combating climate change by requiring the UK to become carbon neutral by 2030.

That would go much further than the party’s current position of achieving net zero emissions before 2050.

But the Tories said the proposals would weaken the UK’s economy and put jobs at risk.

Chris Philp, the Conservative Party’s vice chairman for policy, said: “It’s no surprise that Jeremy Corbyn’s hard-left allies are driving ideological policy that would put businesses at risk and leave ordinary working people paying the price with higher taxes, more debt and fewer jobs.”

Momentum was set up in 2015 and it has been a key supporter of Mr Corbyn, helping the left wing of the party to win control of the Labour machine.

Its decision to now shift its focus towards policy creation represents a potentially major moment in the direction of the Labour Party.