FRANKFURT, West Germany (AP) _ Authorities on Wednesday arrested the former head of a West German company and said he was suspected of a ''leading role'' in building a Libyan plant allegedly intended to produce chemical weapons.

West German and U.S. authorities alleged that the company, Imhausen-Chemie, was the key supplier of material for the plant in the Libyan city of Rabta. Libya claimed the plant was for making pharmaceuticals, but U.S. and West German officials claim it was intended to manufacture chemical weapons.

Juergen Hippenstiel-Imhausen, who was chief of Imhausen-Chemie until March, was arrested Wednesday in the city of Bochum, said prosecutor Holger Preisendanz in a telephone interview.

Hippenstiel-Imhausen is ''strongly suspected'' of violating West German export laws, said the Mannheim prosecutor, who heads the investigation.

In a separate statement, Preisendanz said ''there is the strong suspicion that the accused, Dr. Juergen Hippenstiel-Imhausen himself, had a leading role in the planning and construction of the plant in Rabta, Libya, that was intended for the production of chemical weapons.''

Although the statement referred to Hippenstiel-Imhausen as ''the accused,'' he has not been charged with any crimes.

The ARD television network reported Wednesday that authorities also were investigating Hippenstiel-Imhausen for possible tax law violations.

Hippenstiel-Imhausen is the first person to be arrested in the investigation into the scandal that strained relations between Washington and Bonn earlier this year.

Chancellor Helmut Kohl's government in January initially denied West German companies were involved in the Rabta project, but later acknowledged widespread West German participation, setting off a backlash that embarrassed his coalition government.

The dispute over the plant rekindled tensions between the United States and Libyan leader Col. Moammar Gadhafi. The plant is 60 miles south of Tripoli.

Preisendanz said prosecutors, police and customs inspectors had searched the offices of Imhausen-Chemie in the southwestern town of Lahr and its subsidiary, the Gesellschaft fuer Automation in Bochum.

''The arrest is in connection with the probe into the Libyan plant,'' the prosecutor said.

He said that further arrests could not be ruled out, but added: ''I don't see any cause for that right now.''

Preisendanz emphasized authorities also decided to arrest Hippenstiel- Imhause n to prevent him from fleeing the country.

Imhausen officials said in January that Hippenstiel-Imhausen and his family had gone into hiding after receiving death threats.

In Bochum, judicial authorities released a statement saying they were concerned Hippenstiel-Imhausen might have been trying to hide evidence needed for the investigation.