Shares in CNOOC, China's biggest offshore oil and gas producer, fell in Hong Kong Friday after it replaced Yang Hua as chief executive, the latest in a string of management shake-ups at top Chinese firms.

The company said it had appointed executive director Li Fanrong as replacement with immediate effect, a move seen as part of preparations for next year's leadership change in Beijing.

Its shares were down more than two percent at HK$13.42 in morning trade, mainly due to the weak outlook for oil prices, analysts said.

CNOOC said in a statement that Yang's resignation was due to his responsibilities as president of state-owned parent company China National Offshore Oil Corp., which will require more of his time.

"Mr Yang continues to serve as the vice chairman of the board and will primarily focus on the strategy of the company," it said.

Li is a Western-educated engineer who joined the company in 1984.

Gordon Kwan, head of energy research at Mirae Asset Securities in Hong Kong, said Li was a safety expert whose skills were needed as the company explored for oil and gas in more challenging environments.

"We believe this latest management reshuffle is positive for CNOOC in the long run," he told Dow Jones Newswires.

"Judging by their past track records, Yang Hua's strength is in developing long-term production growth strategy, while Mr Li has extensive experience in operations safety management."

The company's shares have fallen 23.66 percent since the beginning of August.

On November 6, CNOOC announced that Bridas, its joint venture with Bridas Energy Holdings Ltd., had terminated its proposed acquisition of BP's 60-percent stake in Argentine oil company Pan American Energy LLC.

On the bright side, last week the firm said its bid for Alberta oil-sands producer OPTI Canada Inc. had been approved by the Canadian government, allowing the $2.1 billion acquisition to proceed.