The head of a Tokyo-based renewable energy firm will likely admit offering bribe money to Lower House member Akimoto Masatoshi.

Tokyo prosecutors allege the lawmaker received about 30 million yen, or nearly 210,000 dollars, from Japan Wind Development President Tsukawaki Masayuki.

Tsukawaki's lawyer previously claimed that the money was given to a union of racehorse owners jointly established by the two men, and was not a bribe.

But the lawyer says Tsukawaki now plans to admit to the charges.

Akimoto was previously a key member of the main ruling Liberal Democratic Party's renewable energy initiative. The money in question is believed to be related to offshore wind power projects.

Akimoto has stepped down as parliamentary vice minister for foreign affairs, and quit the LDP. He is yet to comment on the allegations.

Akimoto temporarily received a similar sum from Tsukawaki four years ago, when the lawmaker applied to register as a racehorse owner. Prosecutors are believed to be investigating the transaction further.