In the original June 23 referendum across the UK, 52% of voters said they wanted to leave the 28-member European Union.
But many of the "leave" voters apparently quickly regretted their decision when global markets plummeted on the news and experts predicted other dire consequences around the exit. Others complained the "Leave" campaign had been deceiving, with leaders of that side already rolling back on their promises.
Polls showed the majority of younger voters backed remaining in the union.
'Decision must be respected'
Britain's foreign office broke the news to EU supporters Saturday in statement, saying that Prime Minister David Cameron had made clear that the "decision must be respected." Cameron announced after the vote that he would step down in October, saying a new leader would be needed to usher the country through the transition.
More than 4 million signed the petition on the Parliament website, which states that any petition that gains 100,000 signatures will be deliberated by members of Parliament. The foreign office statement did not say why the issue appeared to have bypassed Parliament.
"As the Prime Minister made clear ... the referendum was one of the biggest democratic exercises in British history with over 33 million people having their say," the statement said.
"We must now prepare for the process to exit the EU and the government is committed to ensuring the best possible outcome for the British people in the negotiations."
The petition was ironically started by a Leave campaigner ahead of the vote who feared the Remain side would win. It said that if the Remain or Leave vote came out below 60% based a turnout less than 75%, there should be another referendum.
Turnout was just over 72%. There was no minimum threshold for voter turnout under Britain's EU Referendum Act.