China will formulate a new index to forecast the country's foreign trade trends over a two- to three-month period, a senior customs official said Wednesday.

The China Export Leading Index, which will be released by the General Administration of Customs (GAC) on a monthly basis, will consist of 10 sub-indices, including a new export orders sub-index and an export manager confidence sub-index, said Zhong Baohua, deputy head of the Shanghai Customs District.

"The release of the new index will serve as a basis for the government's macro-economic control and provide some references for export companies' business strategy adjustments," Zhong said.

The GAC will send online polls to 2,000 enterprises, which have been chosen from a pool of 255,000 export companies, to collect data, Zhong said, without specifying when the index will be published.

In recent months, China's foreign trade has slowed due to economic difficulties in key Western markets as well as rising costs for labor and raw materials.

In the first five months of the year, China's foreign trade rose 7.7 percent year on year to 1.51 trillion U.S. dollars, much slower than the 27.4-percent increase registered during the same period last year.