American Airlines is warning that a dispute with its mechanics union could disrupt schedules into the summer, USA Today reports.

The airline has filed a lawsuit against the Transport Workers Union of America, AFL-CIO and International Association of Machinists and Aerospace Workers (TWU), claiming that alleged work slowdowns led by the union have caused 2,200 flight cancellations and delays since February.

American accused mechanics of taking extra time to make repairs on aircraft and refusing to work overtime.

“The odds of this being random as opposed to concerted activity is less than one-in-one billion,” the lawsuit says.

Mechanics at the airline have been negotiating a contract with American since 2015, when the airline merged with US Airways.

A statement from the union said workers are “ready and willing to get back to the bargaining table at any time and negotiate a fair joint collective bargaining agreement, but to do so would take a willing partner”.

“We would much prefer to be at the negotiating table than in a legal battle brought on by American.”