Angry United Airlines executives are accusing pilots of calling in sick in order to disrupt service and pressure the company to reopen contract negotiations.

A lawsuit filed in federal court today charges that the Air Line Pilots Association orchestrated a "sickout" right after United announced cutbacks in jobs and flights.

The union also encouraged employees to refuse extra flight assignments to pressure the airline to jump-start collective bargaining talks, the suit claims.

Such tactics caused the cancellation of 329 flights between July 19 and Sunday, United officials said, and disrupted 36,000 travelers.

"This is an illegal job action," United spokeswoman Megan McCarthy said.

Normally, United and United Express offer about 3,200 daily departures.

United pilots have sharply criticized the leadership of the airline and salaries paid to executives in the face of hard times for the industry.