EU member states are considering how much extra time to give Britain to negotiate a smooth departure from the EU, diplomats said, in a sign the risk of a no-deal Brexit this week has been averted.
EU leaders are due to decide at a special summit on Wednesday whether to delay the date of Brexit from Friday until June 30, as requested by British Prime Minister Theresa May. European Council President Donald Tusk, meanwhile, has proposed a flexible one-year extension.
London needs the extra time to broker parliamentary approval on a Brexit divorce deal negotiated with Brussels. Britain's EU departure has already been postponed from March 29 to April 12.
The decision at this stage is not whether to grant an extension, but how long it should be, EU diplomats said Tuesday on condition of anonymity, following ministerial talks in Luxembourg to prepare for Wednesday's summit.
The length of delay granted "must be proportionate to the objective," EU Brexit negotiator Michel Barnier said following the talks. "It has to serve a purpose, this extension."
"The British side must outline a clear plan with credible political backing," to justify a Brexit extension, added Romanian EU Affairs Minister George Ciamba, whose country holds the rotating EU presidency.
As a condition for any delay - either the shorter option sought by May or Tusk's one-year "flextension" - Britain will likely have to take part in EU elections in late May, diplomats said.
Ministers also discussed a requirement that Britain must not meddle in EU decision making on issues such as senior political appointments or budget negotiations, they added.
May arrived in Berlin on Tuesday for pre-summit talks with German Chancellor Angela Merkel. Both leaders also held conversations with Tusk in the last 24 hours, he wrote on Twitter.
The prime minister is later due to meet French President Emmanuel Macron.
Meanwhile, May faces deadlock at home. British parliamentarians have three times rejected the withdrawal agreement she negotiated with the EU, while also failing to come up with a majority position on any other option.
May's Conservatives are now engaged in talks with the Labour opposition in a bid to find a cross-party compromise that could garner a majority in parliament for the withdrawal deal.
The 585-page legal text provides for a smooth Brexit by extending the application of EU laws in Britain while a new relationship is negotiated. But many Brexiteers oppose some key details.
One of Labour's key demands is that Britain remains in a long-term customs union with the EU, but leader Jeremy Corbyn complained on Monday that the government was sticking to its "red lines".
EU member states are pinning their hopes on these cross-party talks, Barnier said in Luxembourg, while reiterating that the EU would be ready to include a customs union in a political declaration agreed with London on goals for the future relationship.