BEIJING (Reuters) - China's CNOOC Ltd has sold its U.S. subsidiary, together with its upstream oil and gas assets in the Gulf of Mexico, to British chemicals group INEOS, according to a CNOOC statement issued on Saturday.

The Chinese oil and gas major said CNOOC Energy Holdings U.S.A. entered into a sales agreement with a subsidiary of INEOS relating to CNOOC's upstream oil and gas assets in the U.S. part of the Gulf of Mexico.

The deal primarily includes non-operator interests in oil and gas projects such as the Appomattox and Stampede fields.

The firm aims to optimise its global asset portfolio and will work with INEOS towards a smooth transition, said chairman of CNOOC International, Liu Yongjie, in the statement.

CNOOC has been sounding out potential buyers of its interests in U.S. oil and gas fields since 2022.

Reuters had reported earlier CNOOC was considering an exit from operations in Britain, Canada and the United States, on concerns those assets could become subject to Western sanctions because China had not condemned Russia's invasion of Ukraine.