More than 100 drivers who haul goods from the ports of Los Angeles and Long Beach and their supporters protested three Harbor Area trucking companies Monday, calling for the firms to improve working and wage conditions for truckers and to stop retaliating against drivers who want to unionize.

In what they say is the start of “indefinite strikes” at truck yards and marine terminals, protesters swarmed Green Fleet Systems, Total Transportation Services Inc. and Pacific 9 Transportation Inc. to rally against what they say is the misclassification of drivers as independent contractors instead of employees, a practice they said allows the companies to skirt labor laws and avoid paying them fair wages.

“We’re staying out here till the industry changes, until they stop breaking the law,” said former five-year TTSI driver Alex Paz, who said he was fired because he testified to unfair labor practices at his former company. He added that drivers face harassment, retaliation and even death threats from the companies.

Alex Cherin, a spokesman for the companies, denied the allegations. The companies are “discouraged to learn that outside interest groups have again decided to block the rights of these drivers to go to work and earn a living,” according to a statement released by Cherin.

“Time and time again every segment of the industry has rejected the efforts of these groups and their agenda. It is unfortunate that once again we must wait out what has become a distraction.”

Protesters gathered at the Wilmington Waterfront Park on Monday, calling the demonstration a success. The strike left some 400 truckers unable to drive to the ports because they were reportedly told not to come to the terminals for fear that the International Longshore and Warehouse Union would have to honor the picket line. If longshore workers walked off the job, it would cause a significant disruption in the goods movement chain.

“If these trucks aren’t working, there’s nothing to picket,” said Barb Maynard, a spokeswoman for a campaign to organize truckers. “The minute they send a truck down, we’re going to put a picket line right there on that marine terminal.”

Cherin said the decision to not dispatch workers had more to do with the closure of several terminals to commemorate Bloody Thursday, which honors ILWU workers who were killed during demonstrations to establish the waterfront union in the 1930s.

Officials at the Los Angeles and Long Beach ports reported minimal disruption Monday.

The three trucking companies have approximately 400 trucks registered at the ports of Los Angeles and Long Beach — less than 10 percent of those that operate on a regular day, port officials said.

Complicating matters is longshore workers, who have been working without a contract since their six-year agreement with the association representing shipping lines and West Coast port terminal operators expired July 1. The contract covers nearly 20,000 longshore workers at 29 West Coast ports.

Both sides have said they do not want a disruption in the flow of goods.

During past trucker strikes, dockworkers stopped working in solidarity but quickly returned when an arbitrator ruled the job action was not permissible under their contract. Without a contract, the arbitration process is not in effect. If dockworkers walk, their employers can’t force them back to work.

ILWU spokesman Craig Merrilees would not speculate on what dockworkers might do if picketers set up outside marine terminals. A spokesman for the maritime association had no comment.

Meanwhile, both sides released a joint statement late Monday saying that they have agreed to take a 72-hour break from negotiations on a new coastwide contract while the ILWU attends to an unrelated negotiation taking place in the Pacific Northwest.

“During this break, starting at 8 a.m. on Tuesday, July 8, through 8 a.m. on Friday, July 11, the parties have agreed to extend the previous six-year contract, which expired last week,” according to the statement.

The California Trucking Association said it strongly disagrees with the timing of the truckers’ protests.

“While the California Trucking Association respects individuals’ rights to peacefully exercise free speech, the timing of this labor disruption is highly irresponsible,” association CEO Shawn Yadon said in a statement. “At a time when the International Longshore and Warehouse Union and the Pacific Maritime Association have demonstrated great restraint during their contract negotiations, the Teamsters have instead chosen to create disruption.

“If these disruptions spill over into marine terminals, the national economy could lose hundreds of millions of dollars.”

Rep. Janice Hahn, D-San Pedro, who stood alongside drivers Monday, spoke about the economic generators driven by the twin ports and how the drivers who haul goods to retailers should be paid fairly.

“The transportation-related jobs that handle this valuable cargo should be good paying local jobs that fuel economic growth and prosperity throughout Southern California,” Hahn said. “But unfortunately there is one group of skilled, hardworking men and women among us that have been stuck at the bottom of the economic ladder because of long-standing unfair employment treatment. And this unfair treatment must end.”

The Associated Press contributed to this report.

Contact Karen Robes Meeks at 562-714-2088.