German Chancellor Angela Merkel said the European Union needs to guard against the U.K. gaining an economic edge by easing regulation when it leaves the bloc.

On day one after Brexit, the U.K. will be able to “chart a new path” by departing from EU standards on environmental protection, consumer safety and many other areas, Merkel told a business group in Berlin. The EU will need to “develop mechanisms” to offset any such effort and “negotiate our future relations with Britain very thoroughly,” she said.

“Basically, we’re reverse-negotiating a free-trade agreement,” Merkel said Friday. “Not to mention that we don’t have experience in dealing with services in free-trade accords — and that’s an area where Britain is very strong.”

Merkel has been detailing her Brexit stance this week as the EU prepares to start divorce talks with the U.K. after the country’s general election on June 8. Prime Minister Theresa May, presenting her Conservative Party’s campaign platform on Thursday, said “we continue to believe that no deal is better than a bad deal for the U.K.”

Merkel, who presides over Europe’s biggest economy and is seeking a fourth term in Germany’s election in September, warned the U.K. for the second time in three days that it would pay a price for setting a cap on immigration by EU citizens.

“Leaving the EU naturally comes at a price if you aren’t ready to accept the four freedoms of the single market,” she said. “It looks like Britain isn’t ready to accept the free movement of people. So one needs to look at how to balance that out.”