Labour has offered hope the party could still back a second referendum on EU membership at the end of negotiations.
Shadow International Trade Secretary Barry Gardiner said although it was not current Labour policy to have a second vote he could not rule out the possibility.
He stressed that stating support for another referendum would ‘encourage’ the EU to give Britain the ‘worst possible deal’.
It comes after Labour leader Jeremy Corbyn said his party had not fixed its position on the issue while speaking in Lisbon.
Appearing on the BBC’s Sunday Politics, Gardiner was asked whether it was Labour’s policy that there might be another referendum.
He said: ‘No, it’s not the Labour Party’s policy that we might vote again on this… We haven’t made a decision on it.
‘Let’s be absolutely upfront about this: the idea that you would have a second referendum, and that you would say that you’re going to have a second referendum like the Liberal Democrats have done would be to encourage the EU to give you the worst possible deal that there was.
‘So that when you then voted on the second referendum everybody would say ‘well we can’t possibly go there’.’
He added: ‘When we go forward, if we were to have another referendum on the same lines as we’ve had, and it were to be 52/48 the other way what would that achieve? Absolutely nothing – it would then be game on for a third referendum or a fourth.
‘The only way in which in my view you could possibly contemplate a second referendum was if you had the threshold that I believe should have been there in the first place of a two thirds majority, but that I stress is not Labour Party policy, it is not something that we’ve decided and Jeremy articulated the position quite properly yesterday.’