Authorities said Monday they have suspended eight construction companies charged with bid-rigging in defense-related public works projects from participating in government projects for up to five months.

Last week, Tokyo prosecutors indicted three Defense Facilities Administration Agency officials and eight company officials for allegedly rigging bids on construction projects at two U.S. bases in southern Japan, said Taku Shibata, a spokesman at the Land, Infrastructure and Transport Ministry.

The indictments also covered alleged bid-rigging for projects over the past two years at the agency's Ichigaya complex in Tokyo, Shibata said.

The U.S. base projects included five related to runway relocation and facility improvements.

Prosecutors said the defense officials leaked information to the eight companies -- Kajima Corp., Toa Corp., Tekken Corp., Taisei Corp., Obayashi Corp., Penta Ocean Construction Co., Shimizu Corp. and Nissan Rinkai Construction Co. -- so they could place the winning bids.

The eight companies were barred from placing bids in public works for one to five months, mostly in regions where they had allegedly rigged bids, the ministry said in a statement.

Among those hit with the harshest penalties were Taisei and Penta Ocean, which were each suspended for five months in southern areas, the ministry said.

Sadao Iwanaga, chairman of the Japan Federation of Construction Contractors, said at a news conference that "we've been asking the companies to abide by the law."