BEIJING, July 10 -- Bank of China (BOC) shares fell moderately on Thursday after an official TV network alleged that one of its cross-border money transfer services breached money-laundering rules.

BOC stocks listed in the mainland's A-share market fell 0.78 to close at 2.54 yuan per share.

China Central Television (CCTV), China's state TV broadcaster, reported on Wednesday that several BOC domestic branches were suspected of money laundering via its "youhuitong" service, which enables cross-border transfer of large sums of yuan abroad for clients, helping them to transfer their assets overseas.

The bank issued a statement late Wednesday, saying the report is not true and that "youhuitong" has always be done according to regulatory rules.

BOC said that "youhuitong" is an experimental new service that was approved by regulators before it was started in 2011.

"From all the evidence and information we have now, we cannot yet confirm whether such a service provided by the bank can be defined as money laundering, because money laundering is to make illegal income legal," said Guo Tianyong, a bank researcher at the Central University of Finance and Economics.

Currently, China puts a cap on the amount of foreign exchange an individual can purchase within China each year, with the maximum limit set at 50,000 U.S. dollars. Meanwhile, the government's authorization of direct transfer of RMB funds abroad has not been officially announced, even though there have been continuous news reports of some banks offering such business in the past few years.

The CCTV report focused on the BOC bypassing regulatory requirements for maximum purchase of foreign exchange, as yuan funds remitted abroad through the bank's system will be exchanged into local currencies.

"The problem is mainly operational irregularity found with the bank, because it indeed violates an annual quota limit of 50,000 U.S. dollars, and the money transferred has skirted supervision by the foreign exchange regulator," Guo said.

The BOC statement said the youhuitong service so far has only been carried out in a few branches in south China's Guangdong Province.

Li Youhuan, director of the Development and Research Center of Guangdong Social Sciences, told Xinhua that commercial banks have exchanged large amounts of yuan for foreign currencies overseas for clients' emigration or other investment purposes, and such practices have existed for a long time.

Li added that regulatory authorities are also partly to blame for failing their supervisory responsibilities.

China's central bank governor Zhou Xiaochuan said on Thursday that authorities need more time to look into the matter.