Published: Oct 04, 2010 4:56 PM EDT
Updated: Oct 04, 2010 1:56 PM EDT

PHOENIX (AP) - The company that operates one-third of Phoenix city buses has locked out dozens of workers in a contract dispute.

The Arizona Republic reports that negotiations between Veolia Transportation Services and the Teamsters Union broke down Sunday afternoon and the company locked out 60 unionized employees when the old contract expired a minute after midnight.

The company operates 33 of the city's 99 routes.

Veolia spokesman Val Michael says the lockout was necessary to minimize disruptions to bus service.

Veolia has brought in extra workers so the lockout might not affect bus routes when rush hour begins Monday morning.

But the paper says that if the union strikes, thousands of bus riders could be affected.