The membership of the World Trade Organization (WTO) is likely to have a bigger impact on China's oil refining and oil product sales than other sectors of the petroleum industry, said a senior manager.

Lin Qingshan, vice president of leading oil company PetroChina, said the impact could mainly be seen in an oversupply of oil products, increase of competitors and losing control of prices.

A supply surplus would exist in the long run with the flooding of foreign products, which will have an adverse impact on the income of Chinese oil refineries and oil products retailers.

As more companies enter China's oil products market, PetroChina and Sinopec (China Petroleum and Chemical Corporation), China's two largest oil companies which respectively control a significant share of the home market, will face heavier pressure from them.

Because of the oversupply of oil products, prices will change according to market needs, and PetroChina and Sinopec will gradually lose control over the prices.

Lin said PetroChina's refining and sales sectors should learn how to adapt to the changed situation or they would lose out to their competitors.