U.S. regulators have approved China National Offshore Oil Corporation's (CNOOC's) 15.1-billion-USD bid to buy Nexen Inc., a deal that will be the biggest overseas takeover made by a Chinese company.

The approval from the Committee on Foreign Investment in the United States (CFIUS) means the last major hurdle was cleared, CNOOC, China's largest offshore oil producer, said in a statement issued on Tuesday.

Before this, the deal has won approvals from Nexen shareholders, local courts in Canada, the Canadian government, and the National Development and Reform Commission, China's economic planner.

Progresses of the deal with be publicized at a proper time, the statement said.

CNOOC said on Jan. 28 that the closing date for the takeover would be postponed from Jan. 31 to March 2, 2013.

The deal needed U.S. approvals because Nexen, based in Calgary, Alberta, controlled assets in the Gulf of Mexico.