MILTON, Ont. - The union representing workers at an aerospace plant in Milton, Ont., says its members have occupied the facility and stopped production in protest of pension cuts.

Scott McIlmoyle, president of Unifor Local 112, says they entered the Northstar Aerospace west of Toronto at about 4 a.m. Thursday.

He says the shutdown is in response to Northstar refusing to fund a 24 per cent shortfall in workers' pensions at the plant.

The union says the company has announced the relocation of the Milton facility's equipment to Chicago and Windsor, Ont., but will not meet the pension shortfall for workers facing job loss.

McIlmoyle says the company hasn't budged in meetings on the subject and the pension shortfall means workers -- both newly and soon-to-be retired -- will receive about $200 less a month.

Heligear Canada Acquisition Co. says in a statement that the pension was underfunded due to poor management before the company purchased the plant in 2012, and it does not control the pension design or its investments.