Exhibit 99.1

(Incorporated in Hong Kong with limited liability under the Companies Ordinance)

(Stock Code: 883)

UNUSUAL PRICE MOVEMENT

This statement is made by CNOOC Limited (the “Company”) at the request of The Stock Exchange of Hong Kong Limited.

We have noted today’s decrease in the price of the shares of the Company and wish to state that we are not aware of any reasons for such decrease.

We also confirm that there are no negotiations or agreements relating to intended acquisitions or realisations which are discloseable under Rule 13.23 of the Rules Governing the Listing of Securities on The Stock Exchange of Hong Kong Limited (the “Listing Rules”), neither is the board of directors of the Company (the “Board”) aware of any matter discloseable under the general obligation imposed by Rule 13.09 of the Listing Rules, which is or may be of a price-sensitive nature.

Made by the order of the Board, the directors of which individually and jointly accept responsibility for the accuracy of this statement.

By Order of the Board

 CNOOC Limited

 Kang Xin

 Company Secretary

Hong Kong, 23 May 2008

As at the date of this announcement, the Board comprises the following:

Executive Directors Fu Chengyu (Chairman) Zhou Shouwei Wu Guangqi Yang Hua   Non-executive Directors Luo Han Cao Xinghe Wu Zhenfang Independent Non-executive Directors Edgar W. K. Cheng Chiu Sung Hong Evert Henkes Lawrence J. Lau Tse Hau Yin, Aloysius