SEATTLE — The Machinists union has confirmed that negotiations to end a five-week strike at the Boeing Co. have begun.

A note saying talks with a federal mediator were under way was posted Sunday on the union’s Web site. Spokeswoman Connie Kelliher said she did not know where the talks were being conducted.

Boeing and union spokesmen have said the two sides agreed to a media blackout on the negotiations.

An agreement to renew contract talks for the first time since the strike began on Sept. 6 were announced Wednesday.

The International Association of Machinists and Aerospace Workers represents about 27,000 hourly production workers, including about 25,000 in and around Seattle. Key issues include job security, pay, retirement benefits and health care.