The 75-foot dive boat Conception, based in Santa Barbara Harbor, burns after catching fire when anchored off Santa Cruz Island, California, September 2, 2019. (Photo: VCG)

The owners of a dive boat that caught fire and sank off the California coast on September 2, killing 34 people, said on Tuesday they had suspended operations indefinitely during the investigation of one of the state's worst maritime disasters.

The 75-foot Conception, owned by dive tour company Truth Aquatics, burst into flames, killing 33 passengers and a crew member who had been sleeping below decks.

"With the continued calls and request for tours, we want to announce that we are officially suspending all operations of our Truth Aquatic fleet for a to-be-determined amount of time," the company said in a message posted on its website.

"Right now we feel it's important to dedicate our entire efforts to make our boats models of new regulations that we will continue to work on with the US National Transportation Safety Board (NTSB) and Coast Guard," said Truth Aquatics.

The company owns and operates two other dive boats, one which is similar in design to the Conception.

Federal authorities conducting a criminal investigation have searched offices and the two other boats belonging to Truth Aquatics. No criminal charges have been filed in connection with the early morning blaze.

The NTSB has said it will take more than a year to establish a cause of the conflagration and determine wrongdoing, if any.

In a preliminary report issued last month the agency noted that six crew members were asleep in berths behind the wheelhouse when the flames broke out, despite requirements to assign a night watchman.

The crew members who survived by leaping overboard as the burning boat sank into the Pacific Ocean have told investigators that flames coming from the passenger quarters were too intense for them to save those trapped below decks.

Coroner investigators determined that the victims died of smoke inhalation. The final body was recovered on September 11.

Following the incident, the Coast Guard urged boat owners and captains to consider limiting use of lithium-ion batteries and chargers on board, suggesting that investigators are looking into the possibility that the fire was ignited by the devices.

The blackened, burned-out hulk of the Conception was hoisted to the surface near Santa Cruz Island from a depth of 65 feet and taken to the mainland as part of the investigation.