A prosecutor opened a criminal investigation into the Imhausen-Chemie company, which the United States claims helped build a chemical weapons plant in Libya, a judicial spokesman said Friday.

Hans Frey, a spokesman for the prosecutor's office in Karlsruhe, said the investigation was opened by officials in the nearby city of Offenburg.Frey told AP the possible charge being investigated is "a violation of the export control law." He did not elaborate.

Imhausen-Chemie has denied any connection to the Libyan plant.

In a television appearance late Thursday, Chancellor Helmut Kohl said authorities have uncovered new documents implicating West German companies in deliveries of equipment for the plant in Rabta, 40 miles outside Tripoli, the Libyan capital.

Kohl's spokesman, Friedhelm Ost, conceded at a news conference Friday that Bonn officials first learned of "indications" in October that West German companies were involved with the plant.

The government's sharp reversal followed the arrest of a Belgian shipping agent linked to the case and confirmation by Libya's U.N. ambassador that West German companies assisted in the project.

Ost said intelligence sources mentioned the possibility of West German involvement in October but contended they had no evidence then or now that can be used for legal action against any West German companies.