A trade group representing truckers filed a lawsuit claiming plans to clean up the air around the twin ports of Los Angeles and Long Beach place unfair restrictions on their members.

In the lawsuit filed Monday in U.S. District Court, the American Trucking Associations said it does not oppose efforts to clean up the air but is concerned that other measures in the plans violate federal laws by unfairly regulating prices, routes and services.

The lawsuit claims the regulations favor bigger trucking companies over independent truckers and limit the number of trucks allowed to enter the ports, reducing market competition.

Truckers must agree to the plans to retain access to the ports after Oct. 1.

"It's a barrier to entry," said Curtis Whalen of the Intermodal Motor Carriers Conference, an affiliate of the 37,000-member association. "We don't think the ports have the legal ability to do that."

The association wants the court to permanently restrict the plans from being implemented.

Defendants named in the lawsuit include the cities of Los Angeles and Long Beach along with their harbor departments and commissions.

"We feel that the program is legally defensible and we see no problem in continuing to move forward with this plan," said Lee Peterson, a spokesman for the Port of Long Beach.

Both cities passed plans earlier this year aimed at reducing truck pollution at the ports by as much as 80 percent. The plans would require trucks to meet tougher 2007 federal emissions standards by Jan. 12, 2012, along with a $35 cargo fee to pay for the newer, cleaner-running trucks.