"Let's have the referendum [on British EU membership] was to go that way. We would have years of the most difficult negotiations, which would be difficult for the EU as well. And for years we would have such insecurity that would be a poison to the economy in the UK, the European continent and for the global economy as well," Schaeuble said in an interview with BBC broadcaster, answering the question what would happen to the European Union if Britain left the bloc.
He added that possible Brexit would weaken Europe and harm the interests of the United Kingdom.
UK citizens are set to vote on June 23 in a referendum on the country's EU membership, after UK Prime Minister David Cameron and the leaders of the 27 other EU member states reached a deal in February to grant London a special status within the bloc.