Foreign businesses need reassurance that Britain is not going to leave the European Union, Vince Cable has said.
The Liberal Democrat Business Secretary said overseas firms raised concerns with him about the prospect of a British exit but he told them the risk of that happening was "very, very low".
His comments came just days after Chancellor George Osborne warned that the UK could be forced to sever ties with Brussels unless there were major reforms and safeguards for countries outside the eurozone.
The Business Secretary has told worried companies that there is a 5% chance Britain will leave, The Observer said.
Asked by the newspaper whether foreign companies had raised concerns, the Business Secretary said: "The answer is yes. What I say (to businesses) as a government minister is that the risks of us leaving the EU are very, very low ... and I just try to reassure foreign investors."
If the Conservatives win the next election David Cameron has promised an in/out referendum on membership of the EU by the end of 2017 after a process of renegotiating the relationship with Brussels.
International firms including Japanese car giant Nissan have raised concerns about Britain leaving the 28-member bloc.
"I was surprised that Japanese companies and government - which are normally quite reticent, they don't normally go to the barricades - came out so openly and said 'look, we want certainty'," the Business Secretary said.
In a keynote speech Mr Osborne said that the treaties underpinning the EU were no longer "fit for purpose" and failure to reform will condemn the continent to a future of economic crisis and decline, warning: "We can't go on like this."
Mr Osborne stressed the Government's determination to renegotiate the terms of British membership in order that the UK can remain in the EU following a referendum in 2017.
But he said that growing integration of the eurozone had posed threats to the position of Britain's financial services industry and the City of London and said it was "absolutely necessary" to introduce proper legal protection of the rights of EU states not in the single currency zone.
He warned Brussels not to put the UK in a position where it has to choose between adopting the euro or leaving the EU.
Speaking to a conference hosted by the think-tank Open Europe and the Fresh Start Project in London, Mr Osborne said: "I believe it is in no one's interests for Britain to come to face a choice between joining the euro or leaving the European Union.
"We don't want to join the euro, but also our withdrawal from a Europe which succeeded in reforming would be bad for Britain. And a country of the size and global reach of Britain leaving would be very bad for the European Union."