German chancellor Angela Merkel on Tuesday joined British leaders in calling for a more flexible European Union where countries can opt out of integration schemes.

“The Europe of today is no longer a Europe of one speed,” she told a business conference in Berlin.

The conservative leader is keen to keep the British on board to balance against the protectionist instincts of other big member states, like France and Italy.

The United Kingdom puts greater emphasis on trade deals with countries outside Europe and breaking down business barriers, especially for services, within the 28-nation bloc.

“We can say that where there are justified concerns, whether competitiveness or better functioning of the EU, the British concerns are our concerns,” Merkel said.

British prime minister David Cameron seeks a looser relationship with countries on the continent to convince his voters to stay in the bloc. He has promised to call a referendum on membership by 2017.

Germany, by contrast, has called for deeper economic and political integration inside the eurozone — of which Britain is not a member. That has other non-euro states, such as Poland and Sweden, worried.

The Atlantic Sentinel reported in May that Germany’s proposal to link its push for a more integrated eurozone with the United Kingdom’s desire for a less closer union could divide the continent.

Swedish finance minister Magdalena Andersson cautioned in July that a two-speed Europe could affect the design of the single market. “All countries must count,” she argued at the time.

Poles recently elected a government that is more sympathetic to Cameron’s effort. But they are also wary of losing out if the nineteen countries that use the euro increasingly advance at their own pace.

Merkel has drawn one red line. Cameron’s proposal to limit benefits to migrant workers from other European countries cannot breach the principles of free movement and non-discrimination, she has said.

But many other governments, including in Denmark and the Netherlands, do support this British proposal.

Giving national legislatures the right to veto European laws could be another sticking point, especially after Greek parliamentary votes added great uncertainty to that country’s rescue.