China National Offshore Oil Corporation agreed to buy Canadian oil group for $15.1 billion plus debt, as Chinese companies are looking at new resource streams amid the global downturn, the Financial Times reports.

The bid for Calgary-based Nexen would be Cnooc’s largest overseas acquisition since its failed $18.5 billion bid for US-based energy company Unocal in 2005. Cnooc’s cash offer stands at $27.50 a share, representing a 61% premium to Nexen’s closing price on Friday. According to the FT, shares in Nexen rose by $8.76 to $25.82 during morning trading in New York. Nexen has large oil sand and shale gas reserves in western Canada, and oil and gas assets in the North Sea, Gulf of Mexico and Nigeria.

Nexen’s board unanimously approved the deal while shareholders will vote on the deal on or before September 21. Nexen’s interim chief executive told FT: “This transaction will allow for significant investment in our business and opens the door to new opportunities for our employees”.

The deal still requires approvals from regulators in Canada, the US and the UK before it pushes to go through, according to analysts. Canada’s trade minister Ed Fast told the Bloomberg news agency that he expects “reciprocity from China in investment and trade. The Chinese group already made concessions with Ottawa to meet requirements for a “net benefit” to Canada.