German business lobby warns that companies are already delaying investments in Britain.

Joint statement with British Chambers of Commerce calls for clarity on future trading arrangements.

Brexit has already damaged UK-Germany trade.

LONDON — German businesses are already delaying investments and pulling business out of the UK to mitigate Brexit uncertainty, the head of one of Germany's most prominent business lobby groups said.

In a joint statement with the British Chambers of Commerce, Dr Martin Wansleben, the CEO of the Association of German Chambers of Industry and Commerce (known as DIHK in German), said that Brexit is causing businesses to rethink their strategy when it comes to the UK.

"The terms of exit are still completely unclear. Many of our members are reporting that they are already shifting investments away from the UK in anticipation of these barriers," he said.

"Businesses are very concerned that Brexit will have a major negative impact. Not only it could lead to more trade barriers – additional bureaucracy, increased waiting time and stricter border controls resulting in higher costs."

While Brexit negotiations are currently focused on securing exactly how much Britain pays the EU as it leaves the bloc, and will then likely move onto Britain's membership of a customs arrangement of some sort with the EU27, businesses are growing increasingly concerned that not enough attention is being focused on their needs as talks progress.

Banks and financial services firms have been the most vocal about these concerns, with Peter Dixon, chief UK economist at Commerzbank — Germany's second biggest lender — saying earlier in August: "Companies are beginning to think about they're going to do in 12-18 months time. Banks certainly are, we've seen a lot of the banks think about the need possibly to set up offices in the EU," he said.

"That's just sort of the thin end of a wedge which other companies will have to think about as well."

In their joint statement, the DIHK and BCC warned that the impacts of Brexit are already being felt.

"The first effects of the Brexit vote are already being observed: German exports to the United Kingdom were down by 3 percent in the first half of this year compared to the first half of last year, whilst exports to the EU increased with 6 percent in the same period," Wansleben said.

"As Brexit talks continue, it’s clear that companies in the UK and on the Continent all want economic issues to rise to the top of the negotiations agenda," BCC Director General Dr Adam Marshall said.

"There is real business appetite from both sides for a focus on practical, day-to-day business concerns, and a desire for clarity on future trading arrangements."

Trading arrangements are a hot-button issue right now, after the UK government published a position paper earlier in August that put forward an official plan to leave the customs union in March 2019 and negotiate a totally "new" customs relationship with the EU, which would "minimise disruption" and be as "frictionless" as possible.

The plans have been widely criticised, with numerous trade and policy experts saying that the plans are simply unrealistic and will not be able to create the so-called "frictionless" trade the government hopes to achieve.