The German Deputy Foreign Minister Michael Roth has warned the U.K.’s negotiations to leave the European Union “will be very difficult” and that Britain won’t be allowed to “cherry pick” the best that the bloc has to offer.

“If the British want full market access but want to limit the access of workers from Germany, France or Poland, they will find there is no a la carte cooperation in this direction,” Roth, the government minister responsible for European affairs, said at a Berlin event Saturday. “We’ve told the British they can’t expect to pick the best aspects of the EU and leave matters at that.”

Germany is taking a leading role, with Chancellor Angela Merkel having spent the week canvassing opinion across Europe ahead of an EU summit without Britain.

She cited the twin challenges of security and economic growth as leaders prepare to meet in the Slovak capital of Bratislava on Sept. 16. Merkel, the leader of Europe’s biggest economy, began the week of shuttle diplomacy by meeting French President Francois Hollande and Italian Prime Minister Matteo Renzi. She then headed to the Estonian capital of Tallinn, Prague and Warsaw before two more rounds of talks with fellow EU leaders in Berlin on Friday and Saturday.

“People will accept Europe only if it holds out the promise of prosperity,” Merkel told reporters on Friday in Warsaw. “Britain’s exit isn’t just some event, but rather a deep watershed in the history of European Union integration.”

21 maps and charts which will challenge perceptions of Europe Show all 21 1 /21 21 maps and charts which will challenge perceptions of Europe 21 maps and charts which will challenge perceptions of Europe Portugal drinks more wine than France Tindo - Fotolia 21 maps and charts which will challenge perceptions of Europe Young Italians, by some distance, are the most likely to live at home with their parents 21 maps and charts which will challenge perceptions of Europe Britain is on course to overtake Germany as Europe’s most populated country 21 maps and charts which will challenge perceptions of Europe Greek workers work the longest hours in the EU 21 maps and charts which will challenge perceptions of Europe Estonia has, per capita, more drug-related deaths than anyone else 21 maps and charts which will challenge perceptions of Europe The fastest download speeds are to be found in Romania 21 maps and charts which will challenge perceptions of Europe Slovenia, Malta and Poland have the smallest gender pay gaps 21 maps and charts which will challenge perceptions of Europe France hates its leader more than other European countries 21 maps and charts which will challenge perceptions of Europe Eastern and Western Europe are very divided on the issue of gay marriage 21 maps and charts which will challenge perceptions of Europe Germany has the most millionaires 21 maps and charts which will challenge perceptions of Europe Everyone likes Christmas, apart from France 21 maps and charts which will challenge perceptions of Europe Germany accepts by far the most asylum applications 21 maps and charts which will challenge perceptions of Europe The UK and France have some of the most positive views of Muslim people 21 maps and charts which will challenge perceptions of Europe Europe's largest Muslim population is in Germany 21 maps and charts which will challenge perceptions of Europe Danes are the most trusting Europeans, and Cypriots the least 21 maps and charts which will challenge perceptions of Europe Finland has the worst economy in the EU 21 maps and charts which will challenge perceptions of Europe Italy has cut back its military spending more than any other major European Nato member 21 maps and charts which will challenge perceptions of Europe Everyone is sad about the refugee crisis 21 maps and charts which will challenge perceptions of Europe People in Spain are also the most likely to live in flats (Brits are most likely to live in houses) 21 maps and charts which will challenge perceptions of Europe Spain is the most likely to feel neighbourly 21 maps and charts which will challenge perceptions of Europe Luxembourg is home to the highest proportion of foreign nationals

During her tour, Merkel faced pressure from eastern European countries to tighten barriers against migration, exposing differing priorities as the EU seeks to map the way forward after Britain’s vote in June to leave the 28-member bloc.

Romania and Poland’s leaders said Saturday at a joint press conference that the countries agreed their priority in negotiations with the U.K. is to make sure EU citizens, including Poles and Romanians living in U.K., keep their jobs and rights after Brexit talks conclude.

How are Germans feeling about Brexit?

The EU has said negotiations with the U.K. won’t start until Britain formally declares its intentions to leave the bloc. Roth said Germany is hopeful that Prime Minister Theresa May’s government will “send us the letter soon” so that Brexit discussions can begin, acknowledging that there is “no blueprint in the drawer” on a way forward.

Merkel and Finance Minister Wolfgang Schaeuble are likely to address the topic on Sunday. Schaeuble is scheduled to speak at an open house in Berlin, while Merkel is giving an extended interview to one of Germany’s public television channels.