Prosecutors on Tuesday served fresh warrants to the mayor of Ishioka, Ibaraki Prefecture, a former aide to a lawmaker and two others over a 2 million yen bribe in connection with alleged bid-rigging.

Ishioka Mayor Yoshishiro Kimura, 60, Mitsuro Ozaki, 56, a former secretary for a Diet member and now an executive at a Tokyo consulting firm, and the two others were arrested Jan. 15 on suspicion of obstructing a public works tender in March 1999 by providing information to Hitachi Ltd., which won the bid.

Also Tuesday, prosecutors arrested three employees of Hitachi group firms on suspicion of bribing the mayor, who has tendered his letter of resignation to the city assembly but has not formally stepped down.

The Tokyo District Public Prosecutor's Office suspects Kimura received a 2 million yen bribe from Ozaki in return for providing a target price for a contract for electrical equipment for a water purification plant. Ozaki allegedly relayed the information to Hitachi.

The contract was ordered by a waterworks enterprise jointly set up by the city of Ishioka and the neighboring village of Tamari, and the mayor was responsible for setting the target price.

The two others served new arrest warrants are Naoki Kuriyama, 55, an official of a Hitachi subcontractor, and Teruo Shimada, 54, an executive of a local gardening company and a relative of Kimura.

The three who were newly arrested Tuesday are Kazuyuki Fujieda, 53, and Yoshihito Oyanagi, 44, employees of Hitachi Plant Engineering & Construction Co., and Susumu Watanabe, 57, director of Hitachi Plant Construction & Services Co.

Kimura and Ozaki admitted to most of the bribery charges, prosecution sources said.

According to investigations, the mayor received the 2 million yen in cash from Ozaki at his consulting firm Gyosai Toshi Kaihatsu Kenkyujo in Nagata-cho, Tokyo, on July 30, 1999.

Hitachi Plant Engineering & Construction offered 5 million yen to the consulting firm later, investigators said.