Tokyo prosecutors on Tuesday arrested the president of a tech venture that develops the world's fourth-fastest supercomputer on suspicion of defrauding a government institution of ¥431 million ($3.8 million) in subsidies.

The special investigation squad of the Tokyo District Public Prosecutor's Office also arrested another official in connection with the case in the raid on the Tokyo headquarters of PEZY Computing, which was part of the team that developed the "Gyoukou" supercomputer.

According to the prosecutors, President Motoaki Saito, 49, and Daisuke Suzuki, 47, are suspected of illegally receiving the subsidies from the New Energy and Industrial Technology Development Organization after padding expenses for the venture firm's technological development.

In November, Gyoukou was ranked fourth among the world's fastest supercomputer after achieving 19.14 petaflops, or calculating 19,000 trillion times per second.

Saito has earned fame both at home and abroad for advocating the need for more technologically advanced supercomputers. He is known as a pioneer for his miniaturization of energy-saving supercomputers, and has expressed an eagerness to develop the technology, saying he aimed to be the best, not second best.

NHK said it was planning to air a program featuring Saito next Monday but had canceled it, citing the ongoing investigation.

In the February edition of the monthly magazine Seiron, Saito said China is leading in the development of supercomputers.

Expressing his ambition to complete a next-generation supercomputer two years ahead of other countries, Saito told the magazine: "We need about ¥30 billion for that so we have to think about how to finance it."

PEZY Computing was established in January 2010 and is currently capitalized at about ¥940 million. It also produces processors and software.