Prosecutors have raided Obayashi Corp.'s headquarters and other locations to investigate possible fraud in bidding on contracts for a ¥9 trillion ($79 billion) maglev train project, people close to the matter said Saturday.

The prosecutors searched the contractor's head office in Tokyo and other sites from Friday to early Saturday and will question company executives on a voluntary basis, they said.

"We will fully cooperate" with investigators, an Obayashi spokesman said.

Obayashi, one of Japan's four biggest contractors, was hired to help build the new high-speed train line between Tokyo and Osaka by 2045 to be run by Central Japan Railway Co. (JR Tokai).

Obayashi has won four maglev-related contracts with its joint venture partners.

Maglev service between Tokyo and Nagoya are slated to begin on a 286-km stretch of the line in 2027, connecting the two cities in only 40 minutes. That's less than half the 88 minutes it now takes the quickest bullet train to complete the trip on the Tokaido Shinkansen Line.

The railway said it is not aware of any fraud in the bidding process.

The line won't be the world's first maglev line, but it will be the first to use superconducting technology, which will give it a top speed of 500 kph.

Obayashi, established in 1936, has about 8,500 employees and is expanding globally. It posted sales of ¥1.3 trillion in the business year ended March 31.