BERLIN (Reuters) - Germany's pharmaceutical and transport industries - including the aerospace and rail construction businesses - are likely to suffer most from Britain leaving the European Union, a study showed on Thursday.

The Mannheim-based ZEW think tank found these sectors were the most exposed in Germany to the fallout from Brexit but that smaller European countries would take a bigger trade hit.

It said countries such as the Netherlands, Switzerland and Belgium would suffer more than Germany, which has a high degree of diversification of trading partners and business sectors.

Brun-Hagen Hennerkes, chairman of the Family Enterprise Foundation which commissioned the research, said the economic fallout from Brexit was nonetheless hard to predict.

"Even if the German economy is doing well and tax revenues are churning, no one can really foresee the consequences of Brexit," he said in a statement. "No one should rely on the monetary policy of ECB President Mario Draghi."

Fighting the risk of deflation, the European Central Bank has cut interest rates into negative territory, regularly offers banks free loans and has already bought over 1 trillion euros of assets, hoping to boost lending, economic growth and in turn inflation.

British Prime Minister Theresa May has said she would invoke Article 50 of the EU Lisbon Treaty by the end of March next year, starting a two-year divorce procedure.

(Writing by Paul Carrel; Editing by Ruth Pitchford)