BEIJING -- Chinese police have arrested 15 suspects in a bank card fraud case, whose illegal gains were estimated at 10 million yuan ($1.6 million), the Ministry of Public Security said.

The case dates back to April when police in Shanghai found more than 5,000 times of balance check for 359 bank cards between January 15 to 17 that were conducted on 14 POS machines, according to a statement released Sunday by the ministry.

Related cardholders denied having checked balance on the aforementioned POS terminals when contacted by the police. Meanwhile, money on some of these cards were confirmed stolen.

Under joint investigations by police in Shanghai, Jiangxi, Guangdong and Yunnan provinces, a family scam group from East China's Jiangxi province was found behind the fraudulent acts.

According to the ministry, the group consisted of two teams led by two brothers surnamed Xiong. One team was responsible for obtaining card information and passwords through pinhole cameras set up around ATMs in the Myanmar-China border area while the other used the data to make counterfeit cards and withdraw money in Jiangxi and Guangdong.

On July 1, police seized 11 suspects in the three provinces and four in Myanmar along with a number of counterfeit cards, pinhole cameras, POS terminals and cellphones as criminal tools.

The four arrested in Myanmar were escorted back to China on July 2, the ministry said.