Some members of Parliament are calling China's offer to buy Nexen Inc. a bad deal for Canada.

The China National Offshore Oil Co. (CNOOC) has offered $15 billion for the Calgary-based energy company. That offer is currently under review by the federal government.

Green Party Leader Elizabeth May raised her concerns Tuesday about the deal.

“When is someone going to talk about national security? We’re talking not about a commercial venture. We’re not talking about a private sector operation coming from China. We’re talking about a state-owned operation of communist China,” she said.

Calgary West MP Rob Anders said on Monday that he opposes the takeover because China is a "non-benevolent country."

Minister of State for Finance Ted Menzies has said he's heard from people on both sides of the issue.

"I've heard many concerns, varying concerns, concerns about the resource industry, concerns about a foreign company investing in Canada," Reuters quoted Menzies as saying when asked what his constituents were telling him.

"We're hearing comments on both sides of the story, many supportive and certainly some that are concerned. What I'm hearing is more concern rather than actually not understanding the issues."

Industry Minister Christian Paradis has the regulatory duty to approve or block the sale of Nexen to CNOOC, a decision that is supposed to be based solely on whether the deal would result in a "net benefit" to Canada.

If the Nexen deal goes through, it would be China’s biggest overseas energy acquisition, in a campaign of expanding aggressively overseas.