This follows a European Council meeting in March where EU leaders agreed to delay the Brexit date until 12 April 2019, should the withdrawal agreement be rejected.
Talks between the British government and the main opposition parties began earlier this week after a surprise shift in Theresa May's Brexit strategy.
Deal doubts: Brexit supporters in London - the exact nature of the deal still hangs in the balance.
The prime minister has proposed that if UK MPs approve a deal in time, the UK should be able to leave before European Parliamentary elections on 23 May.More news: Maisie Williams "Accidentally'" Reveals Massive 'Game of Thrones' Spoiler
The idea is deeply unpopular with Britons who voted to quit the European Union and chart their own future in a 2016 referendum whose arguments are still being waged to this day.
While any extension would be welcomed by most businesses, which are desperate to avoid a no-deal outcome, a delay until June 30 would still have an economic cost. A Brexit-related vote in Britain's House of Commons on Wednesday ended in a tie, the first time that has happened in a quarter-century.
The EU's remaining 27 leaders, who meet May in Brussels for a summit on Wednesday, have to agree on any offer unanimously and it'll be up to them to forge a common position.
"Extension is a tool, not the solution in itself".More news: Teen tells police he’s missing boy Timmothy Pitzen, last seen in 2011
The Labour party said on Friday talks with the government had made no progress as there was no "real change or compromise" from Prime Minister Theresa May's Conservatives.
Shadow home secretary Diane Abbott said: "We are engaged in these talks in good faith but the Government perhaps has to show a little more flexibility than it seems to have done so far".
The prime minister said the British government would like to agree a timetable for ratification that allows Britain to withdraw from the EU before May 23, but the government would continue to make responsible preparations for the European elections on the date. May had previously dismissed the idea because it bars Britain from striking its own trade deals with global giants such as China and the United States.
Many Labour lawmakers also want a second referendum on the terms of Brexit, which May says would be a fundamental threat to Britain's democracy after the vote to leave. May asked for an identical delay when she first requested a postponement, but the European Union rejected it and only agreed to the shorter April or May extension. Visa-free travel has been one of the concerns of Brits with its exit from the bloc.
On Tuesday, the EU Council and the European Parliament agreed to allow United Kingdom citizens to travel without visas to Schengen Area countries for short stays.More news: US Democrats officially request Donald Trump's tax returns from IRS