Six days into a strike by Boeing Co. aircraft assembly workers, there have been no direct talks between the aerospace company and the Machinists union.

Boeing spokesman Tim Healy said Thursday the company remains willing to negotiate but no talks were scheduled.

The union has not spoken directly with Boeing but remains in daily contact with a federal mediator, said Connie Kelliher, a spokeswoman for the union’s District Lodge 751 here.

The Machinists represent about 25,000 Boeing production workers in the Puget Sound area in Washington state, 1,500 in the Portland, Ore., area and about 750 in Wichita.

Union members walked out last Saturday, after talks during a two-day contract extension failed to produce an agreement. Negotiations with the aid of a federal mediator failed to resolve key issues, which include salary, outsourcing, retirement benefits and health care provisions.

The company said it would not try to assemble planes during the strike. As of July, Boeing reported a backlog of airplane orders totaling $346 billion.

Analysts estimate the strike is costing Boeing about $100 million a day in deferred revenue.

The production workers struck for 24 days during their last Boeing contract negotiations, in 2005.