The European aerospace and defence giant Airbus would reconsider investment in the UK in the event of Britain leaving the European Union, the BBC reported Thursday.
Paul Kahn, president of the 16,000-employee Airbus UK, said Britain must compete for international investment.
"The best way to guarantee this is by remaining part of the EU," he said.
Earlier, Chancellor George Osborne said in a speech to the CBI employers' group that he wants the UK "to be in Europe, but not run by Europe".
Prime Minister David Cameron has promised a referendum on the UK's EU membership by the end of 2017, and the matter has been rising up the political and business agenda.
On Monday, the chairman of construction equipment firm JCB said the UK should not fear an exit from the EU.
And on Wednesday, the president of the CBI, Sir Mike Rake, said businesses should "speak out early" in favour of remaining in a reformed EU.
Mr Kahn, speaking to the BBC's industry correspondent John Moylan, said that with a UK referendum on leaving the EU perhaps less than 18 months away, companies like Airbus needed to be at the forefront of the debate.
"I believe that it is vital for a company such as Airbus to come out and make a stand in favour of Britain remaining in the European Union," he said.