Jeremy Corbyn has ruled out backing a second referendum on the terms of the final Brexit deal, after earlier refusing to do so when questioned by Sky News.
Asked by Sky News correspondent Tamara Cohen whether the party would give voters a say on the final Brexit agreement, Mr Corbyn failed to give a straight answer.
When asked afterwards to clarify the Labour leadership's position, shadow chancellor John McDonnell refused to answer the question 10 times.
But a spokesman for Mr Corbyn later said: "A second referendum is not our policy and it won't be in our manifesto."
In response to Cohen's question, Mr Corbyn had said: "EU negotiations are going on and we have set out our lines on negotiations, primarily it is about gaining and retaining tariff-free access to the European markets.
"We want to work with Europe. We respect and accept the result of the referendum but there still has to be an economic relationship with Europe..."
A Labour spokeswoman earlier said the party would lay out its position on Brexit in its election manifesto but said the "position hadn't changed".
She said: "We have consistently demanded a meaningful vote in Parliament and, as the government, will bring the deal we negotiate to Parliament before it is finalised to ensure democratic accountability."
Conservative Party chairman Patrick McLoughlin said it was "yet more evidence of chaos" from the Labour leadership.
Mr Corbyn launched his campaign in central London, promising not to play by the rules and launching an attack on the ruling "cosy cartels".
He promised to target the rich, claiming he would "put the interests of the majority first" and stand up for people held back by a rigged economic system.
And, with his party trailing the Conservatives in the polls by more than 20 points, he said that the election was not a "foregone conclusion".
Mr Corbyn also hit out at "the wealth extractors", including Southern Rail and former BHS owner Sir Philip Green, and said he would not "doff his cap" to "powerful people".
"They say I don't play by the rules - their rules. We can't win, they say, because we don't play their game. They're quite right, I don't. And a Labour Government elected on 8 June won't play by their rules.
"These rules have created a cosy cartel which rigs the system in favour of a few powerful and wealthy individuals and corporations. It's a rigged system set up by the wealth extractors for the wealth extractors."
Theresa May has made clear a "weak" Labour leader will be the focus of her campaign.
In her first campaign visit, to a Labour marginal in Bolton on Wednesday, the Prime Minister told an invited audience: "There's a very clear choice at this election.
"It's a choice between strong and stable leadership under the Conservatives, or weak and unstable coalition of chaos led by Jeremy Corbyn."
Mr Corbyn has insisted he will not go into coalition with the Scottish National Party, despite Nicola Sturgeon's offer of a "progressive alliance" with Labour and the Lib Dems to keep the Conservatives from power.
It comes as 10 Labour MPs announced they would not be standing for re-election, including former shadow home secretary Andy Burnham.
His announcement comes as no surprise - he said he would not fight another election when he became the Labour candidate for Manchester mayor.
He follows the former Vote Leave leader Gisela Stuart out of the door - she was one of the few Labour MPs to vote to leave the EU - her constituents voted to remain.
Labour veteran Alan Johnson has also confirmed he will not run.