BRUSSELS: A new cross-Channel row erupted Wednesday as Britain threatened to break the terms of the Brexit withdrawal treaty by unilaterally delaying checks on food going to Northern Ireland.

The European Union warned it would respond with "legal means" to the announced move, which it said would undermine a pact meant to protect peace on the island of Ireland.

The Irish government called London's decision "unhelpful", while France said it was "unacceptable".

But the UK government, in a statement after talks between Brexit minister David Frost and EU Vice-President Maros Sefcovic, said the measures were "limited and technical".

Northern Ireland Secretary Brandon Lewis triggered the dispute by announcing that London will delay from April until October 1 a grace period under which food and farm products can flow to Northern Ireland from mainland Britain without customs inspections.

"Lord Frost explained that the measures announced today, following official-level notification to the Commission earlier this week, were temporary technical steps, which largely continued measures already in place," a UK statment said.

The six-month delay is necessary, it argued, "to provide more time for businesses such as supermarkets and parcel operators to adapt to and implement the new requirements in the Protocol."

Britain has chafed at the terms of the January 2020 Brexit agreement it signed, part of which keeps its territory of Northern Ireland in the EU's customs area, essentially creating a customs border down the Irish Sea.

Ahead of the Frost-Sefcovic videoconference, the EU said the announcement amounted to a "violation" of the January 2020 Brexit agreement under which Britain left the European Union.

"This is the second time that the UK government is set to breach international law," Sefcovic warned.

That referred to a previous attempt by London -- later dropped -- to override the protocol in the Withdrawal Agreement relating to Northern Ireland.