House of Representatives member Kanju Sato received the salary of a 51-year-old woman registered as his secretary, even though she did not work for his office, investigation sources said Wednesday.

Sato, 62, tendered his resignation Wednesday from the Democratic Party of Japan. He received the money in cash, paid out from state coffers, via his policy secretary, they said.

The cash was then transferred to several bank accounts of Sato's 52-year-old wife, who also serves as his public secretary, they said.

On Wednesday morning, Aichi Prefectural Police questioned Sato's current policy secretary, Shigeru Kudo, on a voluntary basis to look into how state-paid salaries for secretaries were handled in Sato's office.

Sato has told DPJ officials that the woman did work for his office, but there are no indications that she received any wages, the sources said.

The veteran lawmaker regained his Diet seat in a House of Representatives election in June 2000. At that time, Sato registered three people as aides whose salaries were to be paid out from state coffers: a secretary in charge of policy formulation, his wife and the 51-year-old woman.

Political sources said the policy secretary -- Kudo's predecessor -- received the aides' salaries, which the Lower House secretariat paid in cash.

For at least six months, until he was replaced by Kudo, the policy secretary personally delivered the woman's salary -- a cash-filled envelope -- to Sato.

A Diet member is allowed to have up to three state-paid secretaries.

Kudo said this method of salary distribution at Sato's office has not changed. Kudo or a part-time worker receives the salaries of all the aides in cash and hands the envelopes to Sato.

"I don't know what happens to (the salaries of the other two aides) afterward," Kudo told reporters.