FBI agents combed the offices of six Alaska state lawmakers on Thursday as part of a criminal investigation, according to local news reports and lawmakers not targeted in the probe.

State Sen. Tom Wagoner said FBI warrants showed the agents were seeking information on the states's largest oil service company, VECO, and the recently passed overhaul of state oil-production taxes.

Among the lawmakers who received a warrant from the FBI was state Senate President Ben Stevens, a Republican who is the son of U.S. Senator Ted Stevens, the news reports and other lawmakers said.

Wagoner, who was in the Anchorage legislative office building to chair a hearing on an unrelated subject, said he learned of the searches accidentally.

"I went up to see Ben Stevens and on the way I turned into Cowdery's office and I was turned away by an agent there," said Wagoner, a Republican from Kenai. He was unable to enter Stevens' office, either, he said. "There were federal agents in the hallway," he said.

Executives at privately held VECO are known to be big contributors to state candidates, primarily Republicans. Chief Executive and founder Bill Allen is known to be involved with Republican affairs.

VECO officials were not immediately available for comment.

The lawmakers targeted in the probe were, in addition to Stevens, Sens. John Cowdery of Anchorage, Donny Olson of Nome, Reps. Pete Kott of Eagle River, Vic Kohring of Wasilla and Bruce Weyhrauch of Juneau. All are Republicans except Olson, a Democrat.

FBI agents also used warrants to search offices of three state House members in Juneau, Eagle River and Wasilla, according to local news reports.

During the afternoon raid, staffers and reporters mingled in the hallway outside the offices being searched, and agents were observed through drawn blinds searching papers.

House Speaker John Harris, a Republican from Valdez, said he knew little about the searches.

"There's no evidence of criminal activity on the part of any legislators, as far as I know," he said.