Supporters of a second referendum on Brexit from all of Britain's main political parties on Monday handed in a petition with more than one million signatures to Prime Minister Theresa May's Downing Street residence.
"It is time that we now leave the choice to the British people and allow them to decide," Justine Greening, a former education minister from May's Conservative Party, told AFP.
May has ruled out holding a second referendum, urging MPs instead to approve the deal she has made with EU leaders.
The deal has proved highly divisive and all the signs point to MPs rejecting in a crucial vote next week.
The second referendum campaign has meanwhile gained momentum, particularly with the resignation of two ministers who have said another vote could be a way out of the current political impasse.
"There are no certainties in politics and in Westminster at the moment. But I am more positive and confident than I have ever have been since I've got involved in this campaign," said Labour MP Chuka Umunna, a leading supporter.
"This is for my grandchildren," said Glenys Rampley, 74.
"It's unfair for the young people of this country being deprived of the opportunities that the European Union offers," she said.
Campaigners from the pro-Brexit leave means leave also turned out for a demonstration outside the British parliament.
At the protest, Harry Todd told AFP he was representing the 17.5 million people who voted to leave the EU in the 2016 referendum.
"They are trying to sell off a Brexit which isn't a Brexit," he said, calling for a clean break with the EU.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)