China's forex watchdog has announced plans to monitor and check short-term, abnormal fund inflows in the latest effort to trim the country's huge international payments surplus.

The current account surplus surged more than 36 percent to $91.58 billion in the first half of last year, compared with the same period of the previous year, according to the State Administration of Foreign Exchange (SAFE).

Deng Xianhong, deputy director of the administration, said the campaign will cover foreign currency exchanges, companies, foreign agencies and individuals in China's 10 wealthiest regions, but he did not specify the regions.

The administration also ordered banks in Beijing, Tianjin, Shanghai and Shenzhen that handle foreign exchange services to monitor their own operations, Deng said.

He said the watchdog has investigated 1,914 cases and issued fines totalling 139 million yuan ($17.98 million) in last year's forex campaign.

It also uncovered 70 "underground" banks, or illegal private businesses offering remittance, foreign exchange and other banking services, and illegal foreign exchange centers.

Last year, the administration inspected 2,027 branches of 29 domestic and foreign banks, of which 265 were fined 16 million yuan ($2.07 million) for irregularities in foreign exchange services.

Analysts said the effort will help to prevent economic fluctuations caused by heavy inflows and outflows of short-term capital and slow the rise of China's $1 trillion in foreign exchange reserves.