During their first discussion since Johnson announced plans to break international law by rewriting the agreement signed last year, EU governments resolved to stand firm. The standoff has ratcheted up tension ahead of the final scheduled round of negotiations between Britain and the EU next week.

“The proposals from London that call into question the Withdrawal Agreement are completely unacceptable and we can only appeal to the U.K. to return to the negotiating table,” German Europe minister Michael Roth, who chaired the meeting in Brussels, told reporters. “You have to stop playing around at some stage, we need to have some serious discussions.”

Johnson’s plan has prompted threats of legal action from the EU and has been widely criticized for damaging Britain’s reputation for respecting international agreements. At the same time, EU officials hope it won’t prove fatal to negotiations on future relations.

With only three weeks until Johnson’s deadline to get a deal on that, EU chief negotiator Michel Barnier is to hold talks in London on Wednesday. At Tuesday’s meeting, the bloc’s governments reiterated their support for him and his approach to the negotiations.

Separately, European Commission Vice President Maros Sefcovic, who leads work on the implementation of the Withdrawal Agreement, will meet Cabinet Office minister Michael Gove on Monday to discuss the controversial U.K. Internal Market bill.

“The bill as it currently stands violates the letter and the spirit of the Withdrawal Agreement but we will continue to engage with the U.K. in good faith, building on progress already achieved,” Sefcovic told reporters in Brussels after Tuesday’s meeting.