By CNN's Geoff Hiscock and agencies

HONG KONG, China -- The Bank of China is at the center of another potential scandal.

Chinese media report that bank officials in Guangdong province allegedly embezzled up to 6 billion yuan ($725 million) over 10 years.

The bank, regarded as China's best financial institution, is already in the spotlight after it was fined $20 million by U.S. and Chinese regulators earlier this month over irregular loans made by its New York branch.

Wang Xuebing, a former president of the Bank of China, was sacked on January 12 as head of the China Construction Bank for what Chinese officials said was "negligence" over problem loans at the BOC.

Wang moved from the BOC to the Chinese Construction Bank in February 2000. The problem loans in New York occurred between 1993 and 2000.

A Chinese Foreign Ministry spokesperson said last week that Wang had "major responsibility" for the branch's loans and "relevant departments" were investigating Wang's case.

The latest allegations of financial scandal at the BOC, reported by the business weekly 21st Century Business Herald, cite an unidentified official at the Chinese audit bureau.

According to the Business Herald, the official alleges BOC staff in the southern province of Guangdong, adjoining the special administrative region of Hong Kong, siphoned about $725 million into overseas accounts over a 10-year period.

However, media reports later on Monday quoted the National Audit Office of China as denying the allegations.

A spokesman for the audit office was quoted as saying the report in 21st Century Business Herald -- which is a unit of Nanfang Ribao, or the Southern Daily newspaper group -- contained various inaccuracies.

A Hong Kong-based spokeswoman with the Bank of China declined to comment.

"Because the reports affect the mainland operations and are not related to Hong Kong, it is not appropriate for the Bank of China Hong Kong to comment," she said.

Attempts to reach the bank's Beijing branch for comment were unsuccessful.

But analysts say this latest shock will likely affect the Hong Kong branch. The bank plans to raise as much as $6 billion from an international listing of its Hong Kong operation later this year.

A lack of transparency and suspicions of patronage and cronyism continue to dog the reputations of China's banking sector, Financial Times business journalist Robert Thomson told CNN television Monday.

Investigation of 'great importance'The BOC is one of China's four big state-owned banksAfter Wang's sacking, the Bank of China said on January 18 it attached "great importance" to the investigation of its New York branch by the Office of the Comptroller of Currency and the Chinese central bank, the People's Bank of China.

It said it had taken a "series of forceful measures", including restructuring the branch's management and punishing those responsible for the misconduct.

The OCC, a unit of the U.S. Treasury, said it found "misconduct" by prior management that "resulted in significant losses to the New York branch."

The misconduct "included showing preferential treatment to certain customers of the New York branch who had personal relationships with some members of the New York branch's prior management," the OCC said.

The Bank of China is one of China's four big state-owned banks and is the country's largest foreign-exchange institution. (博讯记者：方向) (博讯boxun.com)