VICTORIA - B.C.'s Opposition New Democrats are calling for an investigation by the auditor general into whether Environment Minister Barry Penner pressured a top government bureaucrat to muzzle two scientists speaking out about environmental concerns.

As proof, NDP environment critic Shane Simpson proffered a five-year-old letter Penner wrote to former deputy environment minister Gord Macatee.

The letter amounts to a call for the silencing of the scientists, Simpson said Tuesday.

"It's a letter that attempts to intimidate the then-deputy (minister), and put pressure on the deputy to muzzle two of his officials who were raising concerns about gravel extraction from the Fraser (River) or the potential for gravel extraction," he said.

Penner, who wrote the letter prior to being named to the Liberal government cabinet, said he contacted the deputy minister on behalf of his constituents who were confused about the responses they were receiving from ministry bureaucrats about gravel removal from the river.

"I was representing the concerns expressed by local governments in my constituency and acting in my role as the member of the legislature to bring forward the concerns of those local governments," he said. "I specifically addressed the letter to the deputy minister to avoid the political involvement of a minister."

Penner said his letter asks for ministry clarification of the policy on gravel removal because ministry staff were telling local governments the B.C. government did not support gravel extraction.

He said the Liberals campaigned on the "environmentally responsible removal of gravel."

"I did my job as an MLA to seek clarification as to what the understanding was of the ministry as to the government policy," said Penner.

He cited a March 2003 letter he received from Macatee in response. The letter said the Ministry of Water, Land and Air Protection supported the core principle of a Fraser River management plan "that gravel removal would be allowed for the purpose of flood protection."

Penner said his letter was not threatening and did not amount to a call for the scientists to be muzzled.

"It means exactly what it says, which is if the staff were not aware of what the policy was, it would be good to inform of what it is," he said.

Almost nine months after Penner wrote the letter to the deputy minister of environment, Dr. Marvin Rosenau, a senior government fisheries wildlife biologist, said he was seconded to the University of British Columbia, and now no longer works for the B.C. government.

Rosenau said in a recent interview that he believes his constant criticism of gravel removal from the Fraser ultimately led to his removal. The other scientist involved was identified as Ross Neuman, who is no longer a member of the Fraser Gravel Technical Committee but still works with the Environment Ministry.

Rosenau said he was critical of a proposed housing development in the Mission area, but his scientific comments opposing gravel removal was the major irritant that led to his movement from government.

"One of them clearly that had a lot of controversy associated with it, was Fraser River gravel removal," Rosenau said. "They basically punted all the technical guys, at least within the Ministry of Environment fisheries section off of the gravel committee, when I was reassigned."

Environmentalists and some scientists say gravel removal impacts fish habitat, but others say the gravel must be taken to control potential flood waters.

Simpson said a federal and provincial moratorium against gravel removal on the Fraser River was not lifted until 2004.

The New Democrats want the auditor general to investigate the removal of the two scientists, as well as the two projects they expressed concerns about.