A joint venture between SK Innovation and Sinopec of China has decided to invest 740 billion won ($653.8 million) to expand its production capacity by some 36 percent, officials in Seoul said Tuesday.

The Sinopec-SK Wuhan Petrochemical joint venture was established in 2013 with the two companies investing 3.3 trillion won. SK Global Chemical, a subsidiary of SK Innovation, holds a 35 percent stake in the venture.

The plant under the joint venture has an annual production capacity of 2.2 million tons of ethylene and other petrochemical materials. With the latest investment, it expects to raise the capacity to 3 million tons a year, which includes 1.1 million tons of ethylene and 900,000 tons of polyethylene. The production also includes 700,000 tons of polypropylene.

The expansion is to be completed by 2020 by revamping the existing plant, not building a new one, the company said.

The investment came amid growing demand for petrochemical products in China. The self-sufficiency ratio of petrochemical products in China will reach 60 percent in the next three years, the company said.

By Cho Chung-un (christory@heraldcorp.com)