French Foreign Minister Jean-Yves Le Drian speaks during a meeting in Cairo, Egypt April 29, 2018. REUTERS/Mohamed Abd El Ghany

DUBLIN (Reuters) - A June summit of European Union leaders is the “ultimate deadline” to make progress on issues related to Northern Ireland’s border, French Foreign Minister Jean-Yves Le Drian said on Sunday.

Brexit minister David Davis told a British parliamentary committee in April that an EU demand for progress by June on the Irish border issue, a major sticking point in Brexit talks, was an “artificial deadline.”

But at a news conference in Dublin with Irish counterpart Simon Coveney, Le Drian said the issue could not be delayed.

“The June deadline is the deadline that must be seen as the ultimate deadline” to find a way to avoid a hard border between Ireland and Northern Ireland and allow progress in Brexit talks, Le Drian said.

Northern Ireland will be Britain’s only land frontier with the EU after its leaves the bloc and while both sides say they are committed to keeping the border with Ireland open, but finding a practical solution has proved elusive so far.

Coveney said a Customs Partnership between the EU and Britain, as championed by some members of British Prime Minister Theresa May’s cabinet but opposed by others, could solve many of the issues required to ensure there is no hard border.

The proposal would see Britain essentially act as the EU’s tariff collector.

Coveney said the Irish government was flexible on how May kept her promise that there would be no physical border infrastructure on the island, but not on whether she kept it.

“We are happy to be flexible if the British government comes forward with some new thinking, but what we are not flexible on is the outcome,” Coveney said.