However, about 200 of the ICBC's e-banking customers from across the country, who claim to have lost sums up to 389,000 yuan (US$48,600), have demanded compensation from the bank.

Experts said that improvements are needed to ensure the security of China's online banking system, noting that the incident would put off many potential customers.

The security of online banking was placed under spotlight recently when the 200 alleged victims of ICBC's defective Internet banking service formed an alliance to safeguard their rights and threatened to take the bank to court.

A number of cases have been revealed recently in which online banking customers suffered losses as a result of hacking, fake websites or viruses.

In the latest incident, a court in East China's Zhejiang Province ordered a branch of the Agricultural Bank of China to compensate Hong Rongyao to the tune of 102,500 yuan (US$12,800) after his password was stolen and a large amount of money was taken from his account.

But the large number of victims of ICBC's allegedly defective online banking system has drawn particular attention.

"We will file a collective lawsuit and ask for compensation for the losses resulting from the loopholes in ICBC's online banking system, and end the bank's infringement of its customers' rights," the organizer of the customer alliance said on its website.

The lender was also accused of failing to deal with hackers and being unable to provide a safe online banking network. Each victim's name, place of residence and the amount of money lost was posted on the site.

A man named Pang Feng from Shanghai lost 389,000 yuan (US$48, 000), the largest amount on the list.

The site also posted a wanted notice for a man, aged around 30, who is suspected of stealing 427,000 yuan (US$53,400) from ICBC's online banking service.

But the bank fought back on Friday. A statement on the ICBC website said that customers' failure to safeguard their card numbers and passwords had caused the losses.

The bank, pointing out that its online banking service has 20 million customers, said that the losses were "isolated cases."

Since 2003, the lender has required its customers to use USB-Shield, a patented customer certificate to help avoid risks such as hacking, fake websites or viruses.

"The large number of alleged thefts shows that commercial lenders' online banking services are not 100 per cent secure," said Li Hong, dean of the banking studies department of Shanghai University of Finance and Economics.

"The incident might have an impact on customers using the service in the future," he added.