CNOOC’s (CEO.NYSE, 0883.HKG) US$15.1 billion takeover of Nexen (NXY.NYSE) suffered a setback Thursday when the Canadian government extended a review of the deal by 30 days, The Wall Street Journal reported. Another extension could follow. Canada’s foreign-investment law says that approval of the acquisition by China’s state-owned CNOOC depends on whether the deal results in a net benefit to the Canadian economy. The government initially takes a 45-day review period before commonly extending the process. Canada’s industry minister Christian Paradis said in a written statement that the required time would be taken to conduct a “thorough and careful review.” Neither company commented on the extension. Canadian politicians remain undecided on the role of China’s state-owned enterprises in Canada, particularly on the sensitive issue of natural resources.