Paradis said once the official proposal is received by his department the offer will be scrutinized to make sure there is a "net benefit" for Canada.
"We showed guidelines in 2009 for state-owned enterprises — this is public, this is transparent so they know exactly how we apply the law."
The Chinese company has made several other investments in Canadian companies over the past seven years, including buying stakes in MEG Energy Inc. and a 60-per cent investment in Northern Cross (Yukon) Ltd.
If the bid by China National Offshore Oil Co. is successful, it would be China's largest-ever overseas acquisition.
Harper's Conservative government has rejected only two foreign takeovers in its six years in office, the most notable being the failed bid by Anglo-Australian mining firm BHP Billiton for Potash Corp. (TSX:POT) in 2010.
In 2008, the Tories blocked the $1.3-billion sale of Vancouver-based MacDonald, Dettwiler and Associates' space-technology division to an American company.
The offer has attracted attention south of the border.
A U.S. senator wants his government to hold up the takeover as a means to press China on its trade policy.
Charles Schumer made his argument in a letter sent to Treasury Secretary Timothy Geithner, who chairs the Committee on Foreign Investment in the United States, a body that reviews foreign investments in U.S. companies.
The New York Democrat wrote that he "sincerely" hopes the friendly deal between CNOOC and Nexen goes through and that Chinese companies continue to invest in the United States.
"I urge you not to miss this opportunity — the largest foreign acquisition ever by a Chinese company — to hold China to the commitments it has made to provide a level playing field for U.S. companies seeking to access Chinese markets.''
Although Nexen (TSX:NXY) is based in Canada, it has offshore holdings in the U.S. Gulf of Mexico and CNOOC said the deal requires approval from regulators in the U.S.
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