MIAMI (Reuters) - Miami city officials, seeking $40 million in union concessions, plan to declare "financial urgency," a move that would allow the city to unilaterally alter employee contracts, the Miami Herald's website said on Thursday.

Quoting Mayor Tomas Regalado, the newspaper said the declaration would be issued by City Manager Johnny Martinez on Thursday and would yield savings needed to balance the city's $485 million annual operating budget.

"The unions are not cooperating with the process," Regalado told the Herald. "We need to have a balanced budget."

Regalado and Martinez were not immediately available to comment on the report, and other city officials declined to comment.

Miami officials are seeking the $40 million concessions from the city's four government-workers unions as part of a plan to plug a $60 million gap in a $485 million budget. Overtime limits for firefighters and higher health-insurance contributions are among the city's proposals.

Part of the budget shortfall is caused by the scheduled expiration of temporary concessions made last year by police and other unions. They told city commissioners on Thursday that Miami's unions had made substantial and repeated give-backs to help ease the city's financial pressures.

Stung especially hard by the U.S. housing collapse, Miami tapped Florida's financial urgency law in May 2010 to redo labor terms that saved the city $80 million. Other Florida cities, such as nearby Hollywood, have also used the law in the past.

(Reporting by Michael Connor in Miami, editing by Kenneth Barry)