Bombardier's Northern Ireland boss Michael Ryan has told staff the business is better off remaining part of the EU.
Michael Ryan sent a memo to his more than 5,000 strong workforce, mostly based in Belfast, to say "it is better for our company that the UK remains within the EU".
He's head of what is one of Northern Ireland's largest employers.
It's understood staff were emailed about the firm's position on the referendum on Thursday morning.
Staff have said the message was also posted on memo boards.
We can confirm that a memo from Michael Ryan, our Vice-President and General Manager, was circulated to employees, advising them of the company’s position on whether the UK should remain within the European Union.
A spokeswoman for Bombardier confirmed a memo had been sent to staff, outlining the firm's position on EU membership.
"We can confirm that a memo from Michael Ryan, our vice-President and general manager, was circulated to employees, advising them of the company’s position on whether the UK should remain within the European Union.
"Whilst there are arguments for and against being part of the European Union, Bombardier Belfast’s position is that the UK remaining within the EU is better for our aerospace business.
"Access to integrated European supply chains is critical to our business, and the free movement of goods across Europe contributes significantly to our competitiveness.
"Our company also benefits significantly from EU investment in research and innovation projects, and the learning opportunities such projects afford through collaboration with other European aerospace companies. Our future is predicated on our ability to remain competitive, and R&D is fundamental in supporting this.
"As one of Northern Ireland’s largest employers, we strongly believe that our competitiveness and future success is better served if the UK remains part of the European Union."