Nissan Motor is not currently considering asking embattled CEO Hiroto Saikawa to resign, two sources told the Reuters news agency on Friday, a day after he admitted to being overpaid in violation of internal procedures.

An internal investigation found that Saikawa and other executives had received improper compensation, Reuters reported on Thursday, raising doubts about Saikawa's pledge to improve governance in the wake of former Chairman Carlos Ghosn's arrest last year for alleged financial misconduct.

"It's not going to happen. I don't think it will," one of the sources told the news agency when asked if Saikawa could resign to take responsibility for the alleged misconduct.

"There's no illegality," the anonymous source said.

Nissan was not immediately available to comment to Reuters.

Saikawa had apologised on Thursday and vowed to return any improperly paid funds as he admitted to Japanese reporters that he had wrongly received stock-related compensation under "a scheme of the Ghosn era".

The improper payments, including tens of millions of yen Saikawa received through a stock appreciation rights scheme, were disclosed on Wednesday at a meeting of Nissan's audit committee, Reuters previously reported.

Nissan's board, which is due to meet on Monday, is expected to discuss potential disciplinary action, the report added.