The UK and France are at a standstill on issues related to fishing licenses

The UK and France clashed again in the post-Brexit fisheries dispute on Sunday, with London forcing Paris to withdraw its threats and rejecting any agreement to try to cool a debate that could harm trade between the countries.

At the G20 summit in Rome, both sides drew different scenes from the meeting between Prime Minister Boris Johnson and French President Emmanuel Macron after the podium, and there was little sign that the dispute would be resolved.

After the meeting, the leaders agreed to try to reduce the conflict, a French official said. But Johnson’s spokesman denied the allegations, urging Macron to move to Paris first if he really wanted to stop the situation.

“It is up to the French to decide whether to back down from the threats they have made in recent days about violating the Brexit agreement. It will be a matter for them,” Johnson’s spokesman told reporters.

Relations with France have been increasingly strained since the UK voted to leave the European Union in 2016. The defense agreement London recently signed with the United States and Australia did little to regain Paris’ confidence.

At the center of the controversy is fishing, which has dominated the Brexit talks for years, not because of its economic significance, but because of its enormous political significance for both leaders. If not resolved, the headline could trigger controversy in the Brexit trade deal early next week.

If the dispute is not resolved, Paris said it could impose specific measures from Tuesday, including tightening some restrictions. The controversy erupted when France accused Britain of issuing only half of the fishing licenses it believed it had.

London has denied the allegations, saying it was issuing fishing licenses in its waters under the terms of the Brexit agreement. The controversy escalated following the capture of a British fishing boat by the French this week.

Both leaders did not appear to want to ease the stalemate, and officials said they both believed they were right.

Macron questioned the credibility of the UK, while British Brexit minister David Frost sought an explanation for what appeared to be France’s desire to punish Britain for leaving the EU.