A SECOND referendum could trigger riots on the streets of Britain, a leading Labour frontbencher has warned.

In a withering slap down Barry Gardiner said Labour colleagues backing a public vote on the final Brexit deal “undermines the whole principle of democracy in this country”.

The Shadow International Secretary said a second referendum would be “very, very damaging” and could even trigger “socially disruptive” behaviour across the country.

His firm warning came as it emerged a string of Labour frontbenchers have polled voters on whether they support a re-run of the 2016 vote amid growing fears the party could ditch its opposition to a second referendum.

Two shadow ministers and one parliamentary aide are all currently promoting web surveys on Brexit.

Shadow public health minister Sharon Hodgson is asking voters if the Brexit deal should be approved in a referendum.

She also asks whether they’d like to see Britain remain in the EU if we are on course to crash out without a deal.

But warning colleagues against a second referendum, Mr Gardiner told the Today programme: “I was a Remainer you know. What we said on the doorstep to people whether Leave or Remain was please, go out and vote on Thursday because what you decide will determine the future of our country for the next 30-40 years.

“If you then say to people we did say that to you, we did give you a vote here, and actually we the Remainers lost the vote, but because you were stupid enough to do what you wanted rather than what we wanted...

“That undermines the whole principle of democracy in this country. You never give more succour to the extreme right as when you cut off the mechanism of democratic change.

“People want to be able to achieve change through democratic means. If they feel that is being denied to them they then turn to other more socially disruptive ways of expressing their views.”

He added: “In any situation, if people feel that the root to change is no longer a democratic root then you look to social disruption, perhaps civil disobedience. This is playing with our democracy, it is playing with the foundations of our country in a way that is really really damaging.”

Meanwhile Jeremy Corbyn admitted that it could take even longer to leave the EU if Labour wins power.

The Labour leader called for a “substantial” transition period to take place at the end of Article 50, and said under his leadership there would be an even softer Brexit than under Theresa May.