China National Petroleum Corp. (CNPC) will do its best to reduce the impact of a crude oil pipeline explosion in Dalian, a port city in northeast China's Liaoning Province, CNPC told Xinhua Sunday.

The fire has been extinguished and no casualties have been reported, according to CNPC, China's largest oil and gas producer and supplier.

Oil has stopped leaking into the sea as a valve has been closed.

The oil that entered the sea has been fenced off and contained, CNPC said.

Monitoring of the air and sea environment has been stepped up in the affected areas, CNPC added.

An explosion hit an oil pipeline of 0.9 meter in diameter at 6:20 p.m. Friday and triggered an adjacent smaller pipeline to explode near Dalian's Xingang Harbor.

Both pipelines, owned by China National Petroleum Corp., caught fire. The blaze of the larger pipeline was extinguished around midnight Friday, but at least five subsequent explosions worsened the fire on the smaller pipeline.

The flames that engulfed Dalian wasn't extinguished until Saturday morning, 15 hours after blasts hit two oil pipelines.