Britain’s Shadow Brexit secretary has said Labour must keep the option of a second EU referendum open.

Following the defeat of Prime Minister Theresa May's Brexit deal, Keir Starmer said the choice lay between instructing the government to negotiate a close economic relationship with the European Union based on a customs union, and a further public vote.

Speaking at a conference in London, he said that with time running out before before Brexit day on March 29, it now appeared "inevitable" the government would have to apply for an extension to the Article 50 withdrawal process.

He drew the loudest cheer, however, when he said Labour stood by the commitment made at the party conference last year in Liverpool that if it was unable to force a general election all options must remain on the table - including another referendum.

"That is a very important commitment. It's a commitment to you, our members and our movement. And it is one we will keep," he said.

"As I set out in Liverpool, a public vote has to be an option for Labour. After all, deeply embedded in our values are internationalism, collaboration and cooperation with our European partners."

Mr Starmer again made clear that he believed that in the event of a second referendum, the option of remaining in the EU must be on the ballot paper.

"I don't think it is any secret I firmly believe there should be a Remain option - and there has to be a genuine Leave option," he said.

He said that with the raft of legislation that still needed to get through Parliament before Brexit, it was difficult to see how an extension to Article 50 could be avoided.

"It seems inevitable to me that the Government will have to apply for an extension of Article 50," he said.

"So, it's time for us to inject some honesty into this debate, and to identify the credible solutions that remain.

"In the coming weeks Parliament will have the chance to take control. That starts by being open about the dilemmas we face, and the credible choices that are still available."

Meanwhile Labour deputy leader Tom Watson has said the party is "oligated" to talk to Mrs May about Brexit if she is offering to do so.

During a question and answer session at the same conference, Mr Watson said that while Labour had to respect the result of the 2016 referendum, it was not offering a "blank cheque".

"We are obligated I think through our sense of patriotism and respect for democracy to have an intelligent conversation on Brexit with Theresa May if she is offering it. But there is no bargain basement Brexit on our agenda," he said.

Party leader Jeremy Corbyn is currently refusing to meet Mrs May unless she rules out a no-deal Brexit.

Mr Watson said that ultimately it might require a second referendum to break the deadlock in Parliament.

"That might be the only way that insurance policy part of our conference resolution can help break the impasse in those Brexit negotiations," he said.