Comprehensive bonded zones in China posted 1.7 trillion yuan ($250.74 billion) of import and export volume in the first seven months, contributing more than 30 percent to the country's total foreign trade growth, People's Daily reported on Tuesday, citing data by the General Administration of Customs.

The import and export volume posted a 14.5 percent growth year-on-year in the first seven months, 16.2 percentage points higher than the growth of the country's overall foreign trade volume, and accounted for 9.9 percent of the total foreign trade volume.

"Currently, there are 144 comprehensive bonded zones," said Chen Zhenchong, a leading official in charge of the customs body, adding the zones are of the highest level of openness, with the most favorable policies, complete functions and simplified procedures in China.

So far this year, 5,452 firms have been newly registered in these bonded zones, up 13.3 percent from a year earlier, Chen said.