A review of Bank of China's financial accounts at the end of 2005 by the country's auditing watchdog uncovered a series of irregularities, the bank said on Monday, adding it had cleared up most of them.

Bank of China said results of an audit by the National Audit Office (NAO), carried out from April through September of last year, had concluded that the bank had "some irregularities and areas in need of improvement".

They included lending practices at some branches that went against government regulations, lack of due diligence in verifying commercial paper transactions and inadequate oversight of financial accounts at some branches, the bank said in a statement on its Web site.

Law enforcement authorities were pursuing a number of criminal cases involving acts committed at some of its branches before it was restructured and subsequently listed in Hong Kong and Shanghai, it said.

The bank said that it had already cleared up most of the deficiencies addressed in the auditor's report, and the majority of the problems had occured before 2004, meaning they would not impact its publicly disclosed financial statements.

The bank added that a public report by the NAO on its audit would be issued after July.

The National Audit Office has vowed to tighten its auditing of banks and other financial firms over the next several years, aiming to beef up their risk controls.

Several major state banks have reported serious cases of embezzlement and fraud over the past few years, tarnishing the image of the industry and casting doubt on the banks' internal controls.