Canadian aerospace firm Bombardier said Thursday it was selling its plant in Northern Ireland, which produces wings for Airbus aircraft, as part of a reorganisation of the business.

"As the company moves to optimise its global manufacturing footprint, Bombardier will pursue the divestiture of the Belfast and Morocco aerostructures businesses," the company said in a statement

"These are great businesses with tremendous capabilities," the Montreal-based firm said.

The company, which axed 490 people in Belfast last year as part of a global cost-cutting drive, is one of Northern Ireland’s biggest employers with around 3,600 staff.

"We understand that this announcement may cause concern among our employees, but we will be working closely with them and our unions as matters progress, and through any future transition period to a new owner," it said.

Michael Mulholland, an organiser for the GMB trade union, demanded "reassurances" for workers.

"Our members — and their families - have already suffered a terrible year," he said.

"Bombardier jobs are absolutely vital to Northern Ireland's economy and it's time workers were treated with the respect they deserve."

The sale of the Belfast facilities was also deeply concerning to Michelle O'Neill, new head of the Sinn Fein party, who noted that the news added to economic uncertainty caused by Brexit.

Previously the company decided to give up control of its new C Series aircraft, now known as the A220, to Airbus in exchange for using Airbus's sales and marketing heft to lift sales.

Since then Bombardier - which has 68,000 employees worldwide - has refocused on business aviation and in particular on its new Global 7500.