LONDON (AP) — Britain’s Brexit minister predicted Monday that relations between the U.K. and the European Union would continue to be “bumpy” amid tensions over post-Brexit trading arrangements.

David Frost said talks with the EU on ironing out the problems were “not hugely productive” so far.

“I think it will be a bit bumpy for a time, but there is a lot of business to be done,” he told the House of Commons European Scrutiny Committee.

Since Britain made its final economic break from the 27-nation bloc at the end of 2020, the two sides have sparred over EU boats’ fishing rights in U.K. waters and new trade arrangements for Northern Ireland.

Post-Brexit trade rules have imposed customs and border checks on some goods moving between Northern Ireland and the rest of the U.K. The arrangement was designed to avoid checks between Northern Ireland and Ireland, an EU member, because an open Irish border has helped underpin the peace process that ended decades of violence in Northern Ireland.

But the new arrangements have angered Northern Ireland’s British unionists, who say they weaken ties with the rest of the U.K. and impose a heavy burden on businesses.

Britain has unilaterally decided to delay bringing in some of the checks on agri-food products, and the EU has launched legal action in response.

Frost said there was “a degree of unsettledness” in Northern Ireland about the arrangements, and urged the EU to show "pragmatism."

The bloc argues that Britain must abide by the legally binding treaty — negotiated by Frost — that it agreed to just last year.

Frost said the U.K. and the EU needed to make progress before the summer, traditionally a time of heightened tension in Northern Ireland, when Protestant groups hold large marches.

Tensions over the new trade rules were a contributing factor to a week of street violence in Northern Ireland cities last month that saw youths pelt police with bricks, fireworks and firebombs.

“Coronavirus restrictions are coming to an end, we all know that the late spring and summer in Northern Ireland can sometimes be turbulent … so we have to take that reality into account,” Frost said.

“I would like to feel that we were making progress with the EU in good time.”