A possible exit of Britain from the European Union (EU) unsettled German companies as most of them were uncertain about the effects of Brexit on their business, a survey found on Wednesday.

Britain is scheduled to hold a referendum on June 23 on its EU membership.

According to a survey by the Federation of German Industries (BDI) and Deloitte, 64 percent of German firms said they were not able to assess the effects of Brexit on their business, 30 percent of firms expected the effects to be negative.

"The uncertainty of German companies on future business relationships with the United Kingdom is tangible," said BDI Director General Markus Kerber in a statement.

The poll said 71 percent of the surveyed German companies expected financial market uncertainty to increase should Britain leaves the EU, while 60 percent expected a rising capital market and exchange rate volatility.

Nearly half of companies foresaw that foreign direct investment would be diverted to the European continent, and 43 percent expected tariffs for German exporters to increase.

"Almost half of the companies concerned greater complexity and rising costs," said Alexander Boersch, chief economist at Deloitte.

Britain is the fifth biggest trading partner for Germany. Currently, some 2,500 German companies have subsidiaries in the country.

An earlier survey found that 61 percent of German companies running business in Britain would scale back their investment if British voters were to choose "Leave" in June 23 ballot

source : xinhua