BERLIN (Reuters) - Britain faces a long period of uncertainty that would be detrimental to jobs and business if its citizens vote to leave the European Union in Thursday's referendum, a German business leader said Tuesday.

Ingo Kramer, president of the Federation of German Employers, told ZDF German television that leaving the EU would have a "fatal result" for Britain that would also have consequences for Germany, given close business ties between the two countries.

More than 3,000 German firms have operations in Britain, he said.

"Sixty percent of Britain's exports go to the European Union or its close trade partners, which shows the importance of Europe for the British economy," Kramer said. "To open that up to uncertainty would be a totally fatal result."

Kramer said it could take a long time to negotiate new trade agreements between Britain and the European Union following a vote for Brexit, and Britain could not choose deals to reduce trade barriers, while blocking access for EU workers.

Kramer said supporters of a British exit wrongly assumed that EU workers were sapping their resources, noting that most such workers had in fact paid taxes and rent, and generally contributed to the UK economy.

"Britain can't just cherry pick the results, choosing one part and not the other," Kramer told ZDF. He said Switzerland and Norway had negotiated similar agreements as non-EU members, but both had also opened their borders to workers.

Kramer said a vote by Britain to leave the bloc would be "egotistical and nationalistic" and did not make sense given the expected negative fallout. However, he said other countries could trigger similar debates in other EU countries.

Two opinion polls on Monday suggested that the "Remain" camp had recovered some group in the referendum vote following the murder of a pro-EU British lawmaker.

(Reporting by Andrea Shalal; Editing by Alison Williams)