The EU’s chief Brexit negotiator, Michel Barnier, has set the British government a deadline of two weeks to give “vital” clarification on the financial commitments it is willing to honour, at the end of a sixth round of Brexit talks that offered scant evidence of any progress, The Guardian reported.

The issue of the border on the island of Ireland has also emerged as a serious challenge for the UK government, with the Irish demanding an urgent and definite commitment that a solution in effect keeping northern Ireland in the single market and the customs union will be found to ensure there is no return to a hard border.

Asked whether it was necessary, as has been suggested in reports, for the British to provide clarity on their intentions within a fortnight, the EU chief negotiator responded bluntly: “My answer is yes.”

Barnier, who noted it had been 500 days since Britain voted to leave, said he needed to establish an “objective interpretation” of Theresa May’s pledge in her Florence speech that no EU member state would lose out as a result of Britain’s withdrawal, and that budget commitments would be honoured.

“This is absolutely vital if we are to achieve sufficient progress in December,” he said. Barnier repeatedly demanded “real and sincere progress”. “If that’s not the case, then we will continue and that will pull back the opening of discussions on the future,” he said.