BRIGHTON — Britain's opposition Labour Party descended into chaos on Monday as it narrowly rejected a grassroots attempt to force leader Jeremy Corbyn to campaign to remain in the European Union and reverse the outcome of the 2016 Brexit vote.

The 119-year-old party's annual congress turned into a showdown between its irreconcilably splintered pro- and anti-Brexit wings in the run-up to Britain's October 31 divorce from its European neighbours after 46 years.

Corbyn's efforts to unite the two sides by staying out of the debate and putting the ultimate decision in the hands of voters have led to a dramatic drop in Labour's support.

But a motion to force the party to "campaign energetically for a public vote and to stay in the EU in (a second) referendum" was lost in a show-of-hands vote that appeared too close to call.

The result means that the party will leave the conference in the same position that it came in – in favour of a second referendum but against openly campaigning for or against Brexit.

It also marks a triumph for the veteran socialist Corbyn -- official leader of Britain's opposition since 2015 – and a painful blow for a clutch of top officials who broke ranks and tried to turn Labour into an unambiguously pro-European party.

"I do not believe this decision reflects the views of the overwhelming majority of Labour members who desperately want to stop Brexit," London's Labour mayor Sadiq Khan tweeted after the vote.

"Labour IS a Remain party."

Corbyn carried the day after an emotional two-hour debate ended with a cliffhanger finish in which no-one initially knew who came out on top.

"In my view, it was carried," congress chair Wendy Nicholls announced after surveying the hands of hundreds of delegates packed into a hall in the English south coast resort of Brighton.

"No, sorry, it was lost," she corrected herself a moment later.

Nicholls then dismissed a plea from one pro-EU delegate who jumped on stage to ask for a recount.

"Whichever way I go with this I'm going to be in trouble," she said to angry shouts from a large corner of the conference floor.

'Lack of leadership'

Yet Corbyn's Brexit strategy has not been resonating with voters so far.

Many have switched allegiance to the unapologetically europhile Liberal Democrats or the populist Brexit Party of 2016 referendum figurehead Nigel Farage.

Two surveys published over the weekend put Labour 15 percentage points behind Prime Minister Boris Johnson's ruling Conservatives and in danger of losing second place to the Liberal Democrats.

"Jeremy Corbyn has again shown a total lack of leadership on Brexit and settled on yet another fudge on the biggest issue facing our country," Liberal Democrats' leader Jo Swinson said after the Labour vote.

'Maximum consensus'

Activists had spent hours deep into Sunday night trying to come up with a single Brexit motion that could be put up for a vote at the conference on Monday.

They ended up with three.

They first passed a motion proposed by Corbyn and backed by the ruling executive in a secret ballot that infuriated numerous delegates over the weekend.

It sees Labour adopting no official Brexit position in the general election campaign.

But it promises to consider coming up with one "through a special one-day conference, following the election of a Labour government".

Labour would then stage a second referendum in which voters would be given the choice of either backing a new Brexit agreement negotiated by Corbyn or staying in the EU.

The second motion was the hotly disputed attempt to get the party to adopt an official "remain" stance.

The third one created the least controversy and was approved.

It differs little from Corbyn's proposal and also requires the party to "build maximum consensus" by remaining neutral. — AFP