BERLIN (Reuters) - Nearly two-thirds of German industrial companies say a British exit from the European Union won't hurt their business, a poll by the Ifo economic institute showed on Wednesday, albeit underlining differences in size and sector.

According to the survey, 61 percent of respondents said a Brexit would have no negative consequences for their business while 38 percent said it would cause damage.

Larger companies, those with more than 500 employees, were more concerned, with 53 percent of them saying a British exit would have negative consequences for their business.

Looking at different sectors, firms in the electronics, automobile and metals industry were most concerned while food and textile companies were the least unsettled, Ifo said.

The head of the BGA trade association said on Monday German exports will grow less than expected this year due to external risks, including a British exit from the EU and uncertainties ahead of elections in the United States and France - Germany's two most important trading partners.

Britain is Germany's third most important export destination. In 2015, German companies exported goods worth some 89 billion euros ($100 billion) to Britain. At the same time, Germany imported British goods worth some 38 billion euros, leaving a trade surplus of around 51 billion euros.

With a total trade volume of 127.5 billion euros, Britain is Germany's fifth biggest trading partner behind the United States, France, the Netherlands and China. For the UK, Germany is the most important trade partner, ahead of the United States.

The DIW economic institute DIW has warned a British exit would likely lead to higher export tariffs, reducing German trade and knocking up to half a percentage point off growth in Europe's biggest economy next year.

(Reporting by Michael Nienaber Editing by Jeremy Gaunt)