Gildan will not take any of American Apparel's stores, but will own its brand and assume some of its manufacturing operations, the source said. The deal is subject to a bankruptcy judge approving it on Thursday, the source added.

American Apparel declined to comment, while Gildan did not immediately respond to a request for comment. The source asked not to be identified because details of the bankruptcy auction are confidential.

The auction for the retailer, famous for its sexually-charged advertising, also attracted an offer from California-based apparel maker Next Level Apparel, a source said earlier on Monday. However, Gildan won after raising its original $66 million stalking horse bid, the source added.

The bankruptcy auction also attracted interest from e-commerce giant Amazon.com Inc (AMZN.O), competitor Forever 21 Inc and brand licensor Authentic Brands Group LLC, which led a consortium to acquire Aeropostale Inc (AROPQ.PK) out of its bankruptcy last year, sources said last week.

American Apparel's struggles show the major challenges facing brick-and-mortar retailers as more consumers shop online.

Gildan plans to assume ownership of American Apparel's manufacturing plants in southern California, one of the largest garment-making operations in the United States with about 3,500 employees, sources have previously said.

The bulk of Gildan's manufacturing takes place in the Caribbean and Central America.

American Apparel filed its second Chapter 11 in November with about $177 million in debt after the failure of a turnaround plan implemented by its owners, a group of former bondholders. The company filed its first Chapter 11 in October 2015, and emerged early last year.

(Reporting by Jessica DiNapoli; Editing by Bernard Orr and Richard Pullin)