British and German businesses are calling on EU negotiators to focus on the countries’ shared economic interests as the third round of Brexit negotiations starts in Brussels.

In a joint statement, the British Chambers of Commerce (BCC) and the Association of German Chambers of Commerce (DIHK) said German and British companies want clarity from the outset on the overall shape of the final settlement.

A number of major issues relevant to businesses are yet to be resolved, including the rights of EU workers in Britain and British workers in the other 27 EU member states.

There is a growing view that talks on Britain’s future trade relationship with the bloc could be delayed beyond the autumn. The EU will decide in October whether Britain has made sufficient progress on Brexit divorce issues, including the thorny subject of an exit bill, before talks move on to trade.

There are hundreds of practical and technical issues, including customs arrangements and tax procedures, that need to be resolved during later stages of the negotiations. Businesses in both the UK and Germany want to see talks move on to these issues, customs in particular, as soon as possible.

Adam Marshall, the BCC’s director general, 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. 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.”

Martin Wansleben, the DIHK’s head, said: “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.”

Wansleben noted that German exports to the UK were down 3% in the first half of this year on a year earlier; while exports to the rest of the EU rose 6%.

A recent BCC survey showed that British firms prefer a longer transition period, with 68% advocating at least three years. A DIHK survey has found that the business outlook of companies that trade with Britain is worsening. They are expecting higher costs from limits on the free movement of workers, taxes, tariffs and increasing bureaucratic hurdles at Europe’s new borders.

Britain is the third-largest destination for German goods exports; while Germany is Britain’s second-largest goods and services exports market.