European aerospace giant Airbus on Monday wrote to its British workforce to warn against the nation's possible departure from the EU, less than three months before a key referendum.

Britons head to the polls on June 23 to decide whether the country remains in the European Union, with recent opinion polls edging in favour of a so-called Brexit -- or British exit from the 28-member bloc.

"We firmly believe that it makes good economic sense to stay inside the EU which has helped make the company the global success story it is today," read the letter signed by top Airbus bosses.

"Our business model is entirely based on our ability to move products, people and ideas around Europe without any restriction and we do not believe leaving will increase the competitiveness of our British based operations.

"We all need to keep in the back of our minds that future investments depend very much on the economic environment in which the company operates."

It added: "Airbus Group's success in the UK is predicated on a highly competitive, integrated European business model."

The letter was signed by bosses including Paul Kahn, the president of Airbus Group UK, and Tom Williams, the chief operating officer of Airbus.

The aircraft manufacturer employs 15,000 people in Britain at 32 locations, including sites at Filton in southwest England and Broughton in north Wales, designing and manufacturing wings. The group has a global workforce of 136,000.

Airbus added Monday that it was "proud" to be the largest commercial aerospace company in Britain and the Royal Air Force's biggest supplier of large aircraft, as well as a leading space and satellite firm.

"Airbus Group has come out strongly in favour of the UK staying in the EU," the letter continued.

"As a successful international company with a strong European heritage we are proud that much of the world flies on British-built wings."

Airbus had already come out in favour of Britain's continued EU membership in May, arguing it would reconsider future investment if Britain quit the bloc.