A petition signed by more than 2.8 million people calling for a new EU referendum has no chance of reversing this week's historic vote to leave, Britain's foremost elections expert has said.

Professor John Curtice, whose exit poll was the only one to predict the Conservatives would win last year's general election, said the referendum was so divisive within mainstream political parties and their supporters that it would be unlikely to form a campaigning issue for some time - let alone spark another public vote.

Thursday's referendum saw 17.4 million (51.9%) votes cast to leave the EU, compared with 16.1 million (48.1%) for remaining part of the bloc, with a turnout of 72.2%, according to the Electoral Commission.

In response, more than 2.8 million people have signed an online petition calling for the Government to implement a rule that "if the Remain or Leave vote is less than 60% based on a turnout less than 75%, there should be another referendum".

Prof Curtice said: "It's no good people signing the petition now, they should have done it before. Even then, these petitions don't always mean a great deal.

"It has passed the 100,000 mark for it to be debated in Parliament. All that means is that some MPs will say, 'It's a terrible shame', others will say, 'Hallelujah'. Then that's the end of it."

Almost 160,000 people also signed a separate petition on the Change.org website, calling on new London mayor Sadiq Khan to declare the capital independent from the UK and apply to join the European Union.

A less well-supported petition on the Change.org website include a similar plea for Brighton and Hove to become a member state of the EU.

The clamour to add signatures to the Government website-hosted petition comes amid dissatisfaction from voters who wanted the country to remain part of the union while anecdotes began to emerge from those who said they regretted voting to leave.

The poll resulted in David Cameron announcing his resignation as Prime Minister while the pound slumped to its weakest level for three decades.