Airbus has written to its UK employees to warn about the risks of leaving the EU, stating that Brexit could result in a cut to its investment in the UK.
In a letter to its staff, Airbus said that it makes "good economic sense" to remain in the 28-member bloc, adding "we simply don't know what "out" looks like".
"Airbus Group's success in the UK is predicated on a highly competitive, integrated European business model," the letter signed by Paul Khan, president of Airbus Group UK, read.
"Our position, which probably does not come as a great surprise to you, is 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. Apart from anything else, we simply don't know what "out" looks like.
"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.
The warning was welcomed by shadow business secretary Angela Eagle, who said the letter from a world-leading business is a welcome intervention which shows "what's on the line for workers and businesses in the referendum".
"Many businesses set up in Britain because we have access to the largest single market in the world and are an outward-looking, proud trading nation. Britain is better off in Europe because it brings us jobs, growth and investment. It is vital that our businesses - large and small - which rely on trade with Europe, can benefit by exporting more and create more jobs here in the UK," she added.
However, leading Grassroots Out MP Peter Bone slammed the claims by Airbus. "The risk for British business and British jobs is remaining in a diminishing European club with a failing Euro currency - a club that stops us from making our own trade deals with the rest of the world," he said.
"Today's statement from Airbus flies in the face of their previous pledge to continue UK operations in the event of Brexit. It is just another case of Project Fear. The remain campaign has nothing positive to say about staying in the EU and just peddles wild and unfounded scare stories," he added.
Pro-Remain campaign group Britain Stronger In Europe disagreed, saying that although the decision is for the British people, Airbus have the right to make their views known to their employees.
"Leaving Europe would be a leap in the dark which, as Airbus’ management say, could affect the economic environment upon which investment depends. Airbus, British business and British workers are without a doubt stronger in Europe," deputy director Lucy Thomas said.
Airbus leaders have already warned about the prospect of Brexit, but this is the first time it has spoken directly to its employees.
The announcement follows a survey by Deloitte of over 100 finance chiefs, which found three out of four (75 per cent) are now in favour of Britain staying in the EU from a business standpoint.