VICTORIA -- The B.C. Crown has been asked to look into whether charges should be laid in two sawmill explosions that killed four workers and injured 42 others earlier this year.

WorkSafe BC said Thursday it has asked for a review of whether companies and individuals violated the Workers Compensation Act.

Prosecutions under the act could result in maximum fines of $652,000 and jail terms of up to six months, said Roberta Ellis, a spokeswoman for the agency.

Investigation reports and files from the Jan. 20, blast at the Babine Forest Products Company in Burns Lake and the April 23 explosion at Lakeland Mills Ltd. in Prince George were sent to Crown counsel, who now will decide whether or not to launch prosecutions under the act, she said.

Earlier RCMP investigations ruled out criminal negligence in both explosions.

But Ellis said WorkSafe BC investigations discovered violations. The inspection reports, which could be used in prosecutions, are not being made public, she said.

"If WorkSafe BC had uncovered any evidence in regards to criminal activity, we would have forwarded that to the police," said Ellis. "This is a decision to refer to the Crown regarding violations of the Workers' Compensation Act."

Lakeland Mills Ltd. and Hampton Affiliates, operators of the Burns Lake sawmill, issued statements expressing concern about WorkSafe BC's decision to refer their investigation to the Crown for possible further legal action.

Both said they have been cooperating with the investigation and want to know sooner rather than later the conclusion of WorkSafe BC's investigations into the causes of the explosions.

"We were surprised by this announcement and disappointed that we are not yet able to see the report of WorkSafe's findings so that we can fully understand what happened that tragic night of the explosion," said Steve Zika, Hampton's chief executive officer.

Zika said because the company has not received any additional information from WorkSafe, it will not comment further.

"We deeply regret the tragic accident that took two of our employees' lives and injured many more, forever impacting our employees and their families," said Zika's statement.

Lakeland's statement said the company is disappointed WorkSafe BC asked the Crown to pursue possible charges against the company.

"It is critical for Lakeland and the industry to do everything we can to ensure that this never happens at another mill," said Greg Stewart, president of Sinclar Group Forest Products, of which Lakeland Mills is a division.

"Lakeland has been cooperating with WorkSafeBC and other regulatory bodies to find out the cause. We anticipated WorkSafeBC would release its report into the cause, so it is disappointing to learn that that information is being withheld."

The Lakeland statement said determining the cause of the accident is a massive and complex forensic exercise. A company investigation is underway, but not yet complete.

But Steve Hunt, spokesman for the Steelworkers union, said the union supports WorkSafe BC's decision to call in the Crown. The Steelworkers represent the estimated 450 workers at both sawmills.

"They referred the case to Crown for potential prosecution, which pleases us," said Hunt. "On the surface, it's difficult to know what the reasons are, but we've been strong advocates for criminal prosecution under the Westray law."

The so-called Westray law, passed by the federal government in March 2004, established new legal duties for workplace health and safety, and imposed penalties for violations that result in injuries or death.

The Westray law was created as a result of the 1992 Westray coal mining disaster in Nova Scotia where 26 miners were killed after methane gas ignited, causing an explosion.

WorkSafe BC issued a background statement Thursday that said similarities were observed at both the Burns Lake and Prince George sawmills.

The statement included WorkSafe BC's consistent emphasis in reports released in May, August and October on maintaining vigorous management of wood dust.

The statement said the mills were processing mountain pine beetle-killed wood during cold-weather periods that included low humidity. It said dust from the beetle-killed wood is drier than normal wood and becomes even drier during cold snaps.

"The explosions in both mills originated in spaces at the lower levels where conveyor systems were receiving and moving wood waste," said the background statement.

"They occurred around meal breaks and band saw changes. Friction from gear reducer motor sets has been identified as the likely ignition source in both explosions; wood dust was the fuel," the statement said.

A gear reducer is part of the motor that runs the conveyor belts that carry wood in plants.

WorkSafe BC issued two hazard alerts on Oct. 30. One warning said gear reducers may overheat and become dangerous and the second cautioned that risk of combustible dust increases in winter conditions where there is low humidity.

In September, Burns Lake mill owner Hampton Affiliates announced the rebuilding of Lake Babine Forest Products with leading-edge safety measures.

Negotiations with the B.C. government and local First Nations were underway in a bid to secure a timber supply for the mill, said Hampton CEO Steve Zika.

Lakeland Mills officials in Prince George said last summer the company is also reviewing whether it has enough timber supply to warrant rebuilding.