Theresa May is holding last-minute Brexit talks with the leaders of Germany and France, with the UK due to leave the European Union (EU) in three days’ time.
Mrs May met Angela Merkel in Berlin, and will meet Emmanuel Macron in Paris, as she urges both to back her request to delay Brexit again until June 30.
After the talks, Ms Merkel said a delay that runs to the end of the year or the start of 2020 was a possibility.
There is a summit on Wednesday when all EU states will vote on an extension.
Cross-party talks in Westminster aimed at breaking the impasse are also continuing.
The negotiating teams include Chancellor Philip Hammond, Environment Secretary Michael Gove and shadow chancellor John McDonnell, with the Labour frontbencher are saying they hoped to “broaden the talks”.
But in a leaked letter seen by the Telegraph, International Trade Secretary Liam Fox has warned that agreeing with Labour over its demand for a customs union is the “worst of both worlds” and will leave Britain unable to set its own trade policy.
The UK is currently due to leave the EU at 23:00 BST on Friday.
Downing Street said Theresa May and Ms Merkel discussed the UK’s request for an extension of Article 50 – the process by which the UK leaves the EU – to June 30, with the option to bring this forward if a deal is ratified earlier.
The prime minister and Chancellor Merkel agreed “on the importance of ensuring Britain’s orderly withdrawal”, a statement said.
Ms Merkel said EU leaders would discuss a “flextension” – a one-year flexible extension – at Wednesday’s summit.
Following a meeting of the EU’s General Affairs Council in Luxembourg, diplomats said “slightly more than a handful” of member states spoke in favour of a delay to June 30 and a majority were in favour of a longer extension.
BBC Brussels reporter Adam Fleming said no maximum end extension date was agreed, although December 2019 and March 2020 were mentioned.
Conditions of a delay were discussed including UK participation in May’s European Parliament elections, no re-opening of the withdrawal agreement and how to guarantee the UK’s pledge of “sincere co-operation” in ongoing EU business.
So far, Members of Parliament (MPs) have rejected the withdrawal agreement Mrs May reached with other European leaders last year. –BBC