(CNN) -- A dispute between American Airlines and its pilots has dragged into its third day, after disrupting hundreds of flights over the weekend. The airline said it expects to cancel 360 flights on Monday, bringing the number of cancellations since Saturday to around 600.

The Allied Pilots Association, which represents American pilots, is conducting a sickout in a dispute over pilots who work for Reno Air, a small West Coast carrier recently acquired by American, according to Tim Smith, a spokesman for the airline.

The pilots union has said the airline is moving too slowly to integrate lower paid Reno Air pilots into the American system.

Salaries for Reno Air pilots are about half those of American pilots. American pilots say they are concerned the airline intends to operation Reno as a separate airline, which they maintain violates terms in their labor contract. Pilots are barred from striking by federal law but can refuse to work overtime.

On Sunday, American canceled 240 of an average 2,250 flights because of a shortage of pilots. About 90 flights were canceled Saturday.

American issued a statement saying that it is trying to book passengers on other American flights or on other airlines.

Negotiations with the pilots union, which represents 9,200 pilots at American, which is the nation's second largest airline, ended last week without a compromise.

The airline said "most of our rank and file pilots continue to do their jobs in their traditional professional manner. We remain optimistic that this situation can be settled promptly."

American acquired Reno for $124 million in November.

Reuters Limited contributed to this report.