PetroChina Company Limited (PetroChina) is to buy a 51.89-percent stake in CNPC (Hong Kong) Limited from its parent company, China National Petroleum Corporation (CNPC), in a bid to further expand its gas business.

The stake would cost 972 million U.S. dollars in cash, said the company in its half-year report on Wednesday.

PetroChina said it would cooperate with CNPC (Hong Kong) to develop gas ventures in end-user markets.

The Beijing-based oil producer said the deal, which was still waiting for official approval from government departments and regulatory institutions, was expected to close by the end of this year.

PetroChina reported a first-half net profit of 53.62 billion yuan, down 34.5 percent from the same period last year, pushed down by fuel price caps and windfall taxes.

Crude oil output reached 435 million barrels, up 3.5 percent, while natural gas output increased 15.7 percent to 923 billion cubic feet.

CNPC (Hong Kong) Limited, also a subsidiary of the CNPC, had 11 gas and oil exploration and development projects worldwide by June.