The vessels were built and delivered by two Shanghai-based shipyards under CSSC - Hudong-Zhonghua Shipbuilding (Group) Co Ltd and Jiangnan Shipyard (Group) Co Ltd. LNG is a particularly clean source of power which can reduce emissions of sulphur and fine particles by 99 percent, nitrogen oxides emissions by 85 percent and carbon dioxide emissions by about 20 percent when compared with fuel.

Li said as competition in downstream is getting fiercer with growing new capacities, the second half will remain tough for Sinopec if it does not update its product portfolio to better meet market demand, such as increasing supplies of low sulphur fuel oil for ship use and boosting refined oil exports.

The Norway-based international certification agency said Chinese industry leaders' focus on decarbonization aligns with the government's new "Blue Sky" plan to tackle air pollution by reducing emissions of sulphur and nitrogen oxides and other pollutants by at least 15 percent from 2015 levels by 2020.

China is to halt sales of diesel with sulphur content above 10 parts per million (ppm) to address air pollution.

From Wednesday, no more diesel with sulphur content of more than 10 ppm will be supplied, according to the National Development and Reform Commission.

Reduction in sulphur content will lower polluting emissions from tractors, locomotives, engineering machinery and boats.