PORTSMOUTH. N.H. – The union representing civilian workers at Portsmouth Naval Shipyard is part of a larger group suing the government over collective bargaining rights.

Paul O’Connor, president of the shipyard’s Metal Trades Council, says the unions are fighting new rules that would give the Department of Defense authority to override existing labor contracts.

The 10 unions, representing more than 700,000 defense employees, filed the suit on Monday in Washington. The unions say the rules, known as the National Security Personnel System, overstep the department’s authority, and are asking a judge to stop the rules from going into effect this month.

A judge has already ruled against similar regulations proposed for national Homeland Security workers, said Matthew Biggs, spokesman for the United Department of Defense Workers Coalition.

Biggs said representatives from labor unions are expected to testify against the new rules at a hearing scheduled by U.S. Sen. Susan Collins, R-Maine., on Nov. 17 in Washington.

“Senator Collins appreciates that certain changes in the regulations were made in response to her concerns, but there may be a need for additional improvement,” said Jen Burita, Collins’ spokeswoman.

A voice mail left Friday requesting comment from the Department of Defense was not immediately returned.

About 5,000 civilians from Maine and New Hampshire work at the shipyard in Kittery.