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Britain's Brexit minister and Treasury chief pressed for German support for a future trade deal that encompasses the important financial services sector as they prepared Wednesday for trips to the European Union's biggest economy.

Britain is to leave the EU in March 2019. London last month secured an agreement with the other 27 countries to move on to the next phase of exit talks — discussing future relations, including trade, and transition arrangements.

Britain wants the U.K.'s vast financial services sector included in talks on future trade ties, but chief EU Brexit negotiator Michel Barnier has ruled that out.

Brexit minister David Davis and Treasury chief Philip Hammond wrote in an op-ed for Wednesday's edition of German daily Frankfurter Allgemeine Zeitung that "the economic partnership should cover the length and breadth of our economies including the service industries — and financial services."

"As two of Europe's biggest economies, it makes no sense to either Germany or Britain to put in place unnecessary barriers to trade in goods and services that would only damage businesses and economic growth on both sides of the Channel," they wrote.

Hammond is due to speak at a closed-doors conference in Berlin Wednesday. Davis is meeting CEOs in Munich Thursday.

The visits come as German leaders are focused squarely on domestic politics, trying to form a new government more than three months after the country's election. Chancellor Angela Merkel and other political leaders are locked in talks on a possible coalition that are due to last until Thursday night.

The British ministers underlined London's argument that "we should not restrict ourselves to models and deals that already exist."

They said that work on ensuring that financial authorities worldwide can cooperate in setting rules and supervising large companies "shouldn't end because the U.K. is leaving the EU."

"On the contrary, we must re-double our collective effort to ensure that we do not put that hard-earned financial stability at risk, by getting a deal that supports collaboration within the European banking sector, rather than forcing it to fragment," the ministers argued.

German government spokesman Steffen Seibert said no meeting was planned with the British ministers.

He told reporters in Berlin that maintaining the unity of the EU's other 27 members remains "of paramount importance" and that will continue to be Germany's "focus."