Democratic Party of Japan lawmaker Kanju Sato tendered his resignation from the main opposition party Wednesday amid allegations that he misappropriated the state-paid salary of a woman falsely registered as his public secretary.

Sato, a 62-year-old House of Representatives member, said he was taking responsibility for "causing confusion," DPJ officials quoted him as saying.

DPJ Secretary General Katsuya Okada did not immediately accept Sato's resignation letter, stating that the party may instead expel him or demand his resignation from the Diet unless he clarifies the issue by the end of the week.

"In my view, if he fails to clearly explain the facts, accepting the letter of resignation would not be the end (of the party's action)," Okada told a hastily arranged news conference after a 20-minute meeting with Sato in Tokyo.

The DPJ will hold a decision-making executive meeting at the end of this week, with the party set to draw a final conclusion on the matter, Okada said.

According to media reports, Sato registered a 51-year-old woman as his secretary from June 2000 through April 2003, although she did not, in fact, work for his office.

He reportedly personally received her salary, which was paid out of state coffers.

During Wednesday's meeting with Okada, Sato claimed that he was still trying to figure out the facts concerning her actual working situation, according to Okada.

"He needs to clearly explain the facts, as a person who had served as home affairs minister and as an executive of the DPJ," Okada said.