London/Brussels – EU President Donald Tusk challenged Britain on Thursday to come forward with its own ideas to prevent a hard border in Ireland following Brexit, hours before he was due in London for talks with British Prime Minister Theresa May.

Split between London and Dublin

On Wednesday, May rejected an EU proposal under which Northern Ireland would remain inside the bloc's customs union, allowing it to trade freely with the Republic of Ireland but effectively creating a border between Northern Ireland and the rest of the United Kingdom.

"Until now, no one has come up with anything wiser than that," Tusk told a pro-business conference in Brussels.

He said he planned to ask May "whether the UK government has a better idea that would be as effective in preventing a hard border between Ireland and Northern Ireland."

Tusk's visit comes ahead of a highly anticipated speech by May on Friday in which she is expected to flesh out her government's vision of Britain's future trading relationship with the European Union.

The row over the post-Brexit Irish border has split London and Dublin, and sharpened divisions between unionists and Irish Republicans in Northern Ireland, which will leave the EU with the rest of the United Kingdom in March 2019.

Late Wednesday, Irish Prime Minister Leo Varadkar also urged May and others opposed to the EU draft to come up with new proposals for the border.

"It’s not OK for people, whether pro-Brexit politicians in Britain or parties in Northern Ireland, to just say 'no' now," Varadskar told Ireland's Newstalk radio.

"It's incumbent on them, if they can't accept the backstop, well then they must detail how option A or B would work," he said.

Tusk to present draft guidelines

But Nigel Dodds, who heads a group of 10 lawmakers from Northern Ireland's Democratic Unionist Party in the British parliament, accused people supporting the EU draft of "attempting to use the hard won peace in Northern Ireland for electoral gain or to block Brexit."

The 10 DUP lawmakers back May's minority government on key votes.

Robin Swann, leader of the smaller Ulster Unionist Party, said no British government could accept the EU's plan.

"It demonstrates complete and utter contempt for Northern Ireland's constitutional position," Swann said.

"Reckless Brexiteers"

Rival Republican Party Sinn Fein said the British government and the DUP had "dismissed the interests of the Irish people, north and south."

"Leaving the customs union is incompatible with avoiding a hard border on the island of Ireland," said Matt Carthy, a Sinn Fein member of the European Parliament.

"Ireland and the other [EU] member states cannot be dictated to by the reckless Brexiteers," Carthy said.

May has insisted that Britain will leave the EU's single market and customs union.

Tusk is due to present draft guidelines next week on the kind of future relationship the EU could have with Britain, based on London's red lines.

"I want to stress one thing clearly: There can be no frictionless trade outside of the customs union and the single market. Friction is an inevitable side effect of Brexit," he told the BusinessEurope conference.