China's five leading petrochemical companies posted combined profits of 27.1 billion yuan last month, an increase of 44.8 percent year-on-year, according to the China Petroleum and Chemical Industry Association (CPCIA).

The five companies are China National Petroleum Corp, China Petrochemical Corp, China National Offshore Oil Corp, Sinochem Corp, and Shaanxi Yanchang Petroleum (Group) Co.

In April, revenue for the five companies' main business was 207.7 billion yuan, a decrease of 28 percent year-on-year, said the association.

"Although the industry has seen some recovery compared with previous months, the demand is still weak and overcapacity still exists in the sector," the CPCIA said in a statement.

The April turnover of China's petrochemical industry was 502.9 billion yuan, down by 8.4 percent year-on-year, said the association. However, it saw 1 percent growth when compared with March.

Domestic oil refining enterprises continue to see good performance in face of the relatively low crude prices. China Petrochemical Corp, the country's largest refiner, saw 48.4 percent growth in profit from a month earlier, according to the CPCIA.

Su Shulin, chairman of China Petrochemical Corp's listed arm Sinopec Corp, said on Friday that the company would lose money turning oil into fuel should crude trade above $60 a barrel and the government prevents it from increasing prices.

Sinopec will be under relatively big pressure if the government doesn't raise prices, Su told reporters after the company's annual general meeting in Beijing.

Global crude prices have risen by over 30 percent to around $60 a barrel currently. China may adjust fuel prices when crude oil costs change more than 4 percent over 22 working days under a pricing formula introduced last December.