A month since his arrest in Japan, former Nissan Motor Chairman Carlos Ghosn continues to deny allegations of understating his compensation as prosecutors grill him on evidence they say shows his pay was set and thus legally required to disclose.

Ghosn has told prosecutors at a Tokyo detention center that he did not commit to any compensation, according to sources. He is scheduled for release Thursday but could be held until Dec. 30 if the court approves prosecutors' request for an extension.

Prosecutors apparently have obtained a set of documents that they say show Ghosn's decided-on pay. "Agreement on compensation" documents signed by Ghosn and a former chief of Nissan's secretarial office break down the chairman's remuneration into "total," "paid" and "postponed." The phrase "fixed remuneration" is used in certain documents.

A table said to outline details of these compensation agreements is believed to include handwritten edits by Ghosn.

Greg Kelly, fired as a representative director days after he and Ghosn were arrested, and CEO Hiroto Saikawa had also signed a post-Nissan noncompete agreement for Ghosn listing payments for him in the form of consulting fees.

Ghosn said he had signed the documents as a guide to his desired pay, based on similar practices of CEOs at American automakers. He has maintained that his pay after stepping down as chairman would be set by the CEO rather than fixed. He also said Kelly had assured him that the reporting procedures were legal.