Sadiq Khan has urged Labour members not to accept any “compromise” on Brexit amid a major row at the party’s annual conference over its stance in a second referendum.

In an attack on Jeremy Corbyn’s plan to delay making a decision on whether Labour would campaign against Brexit, the London mayor told members: “Do not accept a fudge.”

Mr Khan became the latest senior Labour figure at the gathering in Brighton to insist that the party must commit to keeping the UK in the EU.

He said Labour MPs must be whipped to oppose Brexit and, attacking suggestions that Mr Corbyn could decline to endorse any outcome in a future referendum, claimed that staying neutral was “not an option”.

The Labour leadership is facing an angry backlash over the issue after grassroots activists and MPs, including senior shadow cabinet ministers, demanded that Mr Corbyn come out firmly for Remain.

Brexit and climate protests at Labour party conference: In pictures Show all 12 1 /12 Brexit and climate protests at Labour party conference: In pictures Brexit and climate protests at Labour party conference: In pictures Labour leader Jeremy Corbyn walks past anti-Brexit campaigner on the second day of the party conference in Brighton AFP/Getty Brexit and climate protests at Labour party conference: In pictures A protester holds a sign mocking Labour leader Jeremy Corbyn's Brexit stance at the party conference in Brighton EPA Brexit and climate protests at Labour party conference: In pictures Activists from anti-climate change movement Extinction Rebellion march on the Labour conference in Brighton AFP/Getty Brexit and climate protests at Labour party conference: In pictures Delegates take part in an informal vote on Labour's Brexitr stance at the party conference in Brighton AFP/Getty Brexit and climate protests at Labour party conference: In pictures Shadow foreign secretary Emily Thornberry leads a march in support of a second referendum on Brexit Getty Brexit and climate protests at Labour party conference: In pictures Anti-Brexit protesters take part in a People's Vote rally during the Labour party conference in Brighton EPA Brexit and climate protests at Labour party conference: In pictures Extinction RebelliActivists from anti-climate change movement Extinction Rebellion march on the Labour conference in Brightonon EPA Brexit and climate protests at Labour party conference: In pictures Extinction Rebellion activists march on the Labour conference in Brighton AFP/Getty Brexit and climate protests at Labour party conference: In pictures A delegate arrives carrying a briefing from the Labour Representation Committee to the Labour party conference in Brighton Getty Brexit and climate protests at Labour party conference: In pictures Prominent anti-Brexit campaigner Steve Bray protests on Brighton beach during the Labour party conference Reuters Brexit and climate protests at Labour party conference: In pictures Anti-Brexit protesters take part in a People's Vote rally during the Labour party conference in Brighton EPA Brexit and climate protests at Labour party conference: In pictures Activists raise a banner calling for the Labour party to restore the original Clause 4 of its constitution, which would pledge the party to nationalising all industry Getty

The Labour leader is instead proposing that the party should not decide its position until after a general election.

In a “direct appeal” to delegates at the conference, Mr Khan said members should reject any delay in deciding what Labour’s stance in a future referendum would be.

In a statement released to The Independent and later posted on Facebook, he said: “Labour has come to a vital crossroads. At conference this week, we have the opportunity to come together to define how we seek to deal with the biggest challenge facing our country – Brexit.

“Labour’s values of solidarity, social justice and internationalism are clearly best served by remaining in the European Union.

“So I’m making a direct appeal to delegates at Labour conference: do not accept any ‘compromise’ on Brexit, do not accept a fudge, do not delay us setting out what our stance would be in any future referendum.

He added: “Labour is a Remain party and we need to make this official by making it our policy to campaign to stay in the European Union under all circumstances – and to whip all our MPs to back that position.

”Staying neutral in the face of the biggest economic and social threat to our country for decades is simply not an option.”

“It’s time for Labour to commit to stopping Brexit – not only by promising to give the British public the final say, but by pledging to throw all our energy behind the campaign to stay in the European Union.”

The Brexit plan put forward by Labour’s ruling National Executive Committee (NEC) say the party supports another referendum but would ”only decide how to campaign in such a referendum – through a one-day special conference, following the election of a Labour government”.

But activists are hoping to force through an alternative motion that commits the party to backing Remain.

On Saturday, shadow foreign secretary Emily Thornberry became the latest MP to dissent from the official line by arguing that the party should “lead the campaign to Remain.”