China's petrochemical industry expanded at much slower pace in the first quarter amid the economic slowdown, according to data released by the National Development and Reform Commission (NDRC) on Monday.

Petrochemical industrial production rose 16 percent annually to reach 2.4567 trillion yuan ($391.3 billion) in the first quarter, decelerating further from 22.1 percent in the fourth quarter of last year, according to NDRC.

From January to March, the petrochemical sector processed 114.91 million tonnes of crude oil, up 3.1 percent year-on-year, while refined oil products added 5.5 percent annually to reach 69.15 million tonnes, according to NDRC.

Investment of the petrochemical sector, however, kept rapid growth during the first quarter, with the combined investment amounting to 202.4 billion yuan, up 33.5 percent year-on-year.