The head of Nissan has warned the car maker would "reconsider" its future in the UK if it left the European Union.
Carlos Ghosn, chief executive of the Japanese motoring company, told the BBC it would re-evaluate its position if the UK was to leave the EU.
Speaking at the launch of Nissan's new Qashqai model, he said: "If anything has to change we (would) need to reconsider our strategy and our investments for the future."
But he added that he considered such an exit unlikely.
The new Qashqai will be built at Nissan's Sunderland site, which employs 6,500 workers.
Prime Minister David Cameron has promised a vote on EU membership in 2017 if the Conservatives win the next general election in 2015.
Yesterday Lord Jones of Birmingham - who as Digby Jones was director general of the CBI - said Britain must be ready to leave the EU to boost its competitiveness in the open market.
Writing in The Times, he warned that the EU was a "job destroyer" and that leaving would not be an "unattractive option".
Asked about the prospect of Britain leaving the EU, Mr Ghosn told the BBC: "Obviously it's going to be a major factor happening and we are going to need to consider what does it mean for us for the future.
"If anything has to change, we need to reconsider our strategy and our investments for the future."
John Mills, co-chairman of the Business for Britain group, which is seeking reform of the UK's EU membership, told BBC Radio 4's Today programme: "If Britain were to leave the EU - and that's not what Business for Britain is advocating - I think that Nissan and any other car company would have to take a view as to what the prospects were, particularly if we continue to have free trade with Europe, which is very likely to happen.
"What we are saying is that if there's renegotiation then a much larger proportion of British business would want to stay in. I think Mr Ghosn would be wise to support what we say, which is to push for these negotiations to be successfully accomplished."