Asia's largest oil refiner, Sinopec Corp, and the world's biggest chemicals maker by market value, Saudi Basic Industries Corp (Sabic), received regulatory approval from China to develop a previously agreed-to project into a full-fledged venture in Tianjin.

The $3-billion complex, to be operational in September this year, will have an annual capacity of 3.2 million tons of petrochemicals, including ethylene, the primary building block for petrochemicals, and all other downstream products, Sinopec said on its website.

The target production capacity of this 50-50 joint venture was first set at 4 million tons in June 2008.

The project will give the Middle Eastern chemical giant a solid foothold in the Chinese petrochemicals market as China's demand for plastics and other chemical-based products rises.

"The world's new demand for petrochemicals comes from China, and the project is part of a move by Sabic to diversify from its total dependence on the US market," said Lin Boqiang, an energy expert who was involved in the preparation of the project.

Sinopec sales were $20.78 billion last year.