Sinopec, the country's leading oil refiner, said on Thursday its net profit in the first half of the year was expected to decline by more than 50 percent.

It's net profit during 2007's January to June period was 34.93 billion yuan ($4.99 billion).

The company attributed the drop to big losses in its refining business. Chen Ge, a Sinopec official, said earlier that Sinopec lost about 3,000 yuan for each ton of production, due to the sharp gap in oil prices on world and domestic markets.

The situation became even worse as the world oil price continues to stay at a high level. The crude oil price topped $110 per barrel in March, exceed $120 in May and stayed around $140 currently.

Despite the 7.4 billion yuan of subsidy provided by the central government this year, the company saw its net profit reduced 65.78 percent in the first quarter over the same period last year.

Shares of Sinopec closed at 10.31 yuan in Thursday's trading, down 0.09 yuan or 0.87 percent from the previous close.