TOPEKA, Kan. - A man identified by the FBI as a member of the anti-government Freemen group was arrested yesterday after deputies found what they called a bomb-triggering device in his car.

Scott Roeder, 38, of Silver Lake, Kan., was arrested in Topeka and held on charges of criminal use of explosives, driving with a suspended license and failure to carry registration and insurance.

Roeder was stopped because his car didn't have a legitimate license plate. Instead, it had a tag indicating the driver was a "sovereign" citizen and immune from Kansas law.

The same type of tag is sometimes used by Freemen, whose members in Montana are in the fourth week of a standoff with federal agents.

Roeder's name is included on an FBI list of Freemen, said Shawnee County Sheriff Dave Meneley.

In Roeder's trunk, authorities found fuse cord, a pound of gunpowder and two nine-volt batteries, one wired to a switch - the alleged triggering device. Ammunition and a blasting cap also were found in the car.

In Montana, meanwhile, federal agents increased security around the barricaded Freemen compound yesterday. And the FBI field commander refused to see Michigan Militia leader Norman Olson.

Olson said he had come Montana to help the FBI avoid "a field of battle."

The FBI has headquarters in Jordan, Mont., about 30 miles from the Freemen's farmhouse.