The Tokyo High Court on Tuesday ordered a former executive of Mitsubishi Hitachi Power Systems Ltd. to pay a ¥2.5 million fine over bribery in Japan's first case involving a plea bargain, nullifying a suspended prison term delivered by a lower court.

Satoshi Uchida, 66, had been sentenced to 18 months in prison, suspended for three years, by the Tokyo District Court last September for conspiring with two subordinates in charge of logistics to bribe a senior Thai official in a power plant project in the Southeast Asia country.

The high court ruled the testimonies of the two subordinates that Uchida had approved giving a bribe were not credible.

"(Uchida) was consistently hesitant and urging them to come up with alternatives. The district court ruling ... leaves reasonable doubt," said Presiding Judge Yoshifumi Asayama.

Nonetheless, Uchida was in a position to stop the two from bribing an official of the Ministry of Transport in Thailand but failed to do so, according to Tuesday's ruling.

The two paid 11 million baht ($347,000) in February 2015 to the official, who informed them the company had failed to meet necessary conditions for unloading cargo. The subordinates have already been convicted of bribing the official.

Plea bargains were introduced in Japan in June 2018, and under the deal, signed by prosecutors and Mitsubishi Hitachi Power, the Yokohama-based company was exempted from indictment in exchange for cooperation during the investigation and trial.

The plea bargain system was also later used in charging former Nissan Motor Co. Chairman Carlos Ghosn with alleged financial misconduct, after a deal was struck between two of his former close aides and prosecutors.