THERESA May’s hopes of making progress in Brexit negotiations by the end of the year are hanging in the balance with deadlock over the Irish border.

The Prime Minister is due to meet European Commission President Jean-Claude Juncker today to assess whether sufficient progress has been made on citizens’ rights, the “divorce bill” and the border.

Senior figures have cast doubt on her ability to keep an open border in Ireland, while also monitoring the movement of goods and people in and out of the EU.

Tony Blair, the former prime minister, said the EU cannot allow the continued free flow of goods in Ireland if the Tories stick to their commitment to take Britain out of the single market and customs union.

German MEP David McAllister, an ally of Chancellor Angela Merkel whose father is from Glasgow, said the chances of making progress by the end of December are “50/50”.

Mr Blair said: “If there is a hard border the EU will say the same rules must apply (in Ireland) as applies to any other hard border with the EU.”

He said a “bespoke” deal specifically for Northern Ireland is unlikely to prove acceptable to unionists, and acknowledged that Brexit was “problematic” for the peace process.