The United Auto Workers union sued General Motors Co. in federal court Tuesday, contending the Detroit automaker owes a union-run retiree health care fund $450 million, The Detroit News reported.

The suit, filed in U.S. District Court in Detroit, contends that General Motors Corp. agreed in June 2007 to pay $450 million to settle a UAW claim against Delphi Corp., GM's former parts unit, in the supplier's bankruptcy.

Delphi did not acknowledge the claim, and the company's best assets were purchased by a successor company, Delphi Holdings LLP, which exited bankruptcy Oct. 6.

Under the terms of the claim settlement, the GM payment to the UAW was to be made after Delphi exited bankruptcy.

GM filed for bankruptcy in June. The automaker's best assets were acquired by a government-sponsored entity known as General Motors Co.

The UAW contends in its lawsuit that the "new" GM agreed to assume all of its labor contracts with the UAW -- including the 2007 deal among GM, Delphi and the UAW.

But GM disagrees. On Oct. 29 the UAW sought the payment from the automaker. On Nov. 11, GM refused to make the payment.

The UAW says the payment was to be made to its voluntary employees' beneficiary association -- a fund that now pays for hourly retiree health care.