OTTAWA - Natural Resources Minister Joe Oliver no longer talks about "radicals" trying to "hijack" environmental hearings for the Northern Gateway pipeline proposal, but he is backing tougher scrutiny for environmental charities.

"We want charitable organizations to comply with the law, and the law says that the vast bulk of their activities and money must be spent in charitable activities," Oliver said in Saskatoon, Sask. "Any charitable organization that complies with the law doesn't really represent a problem."

His comments come a day after Canada Revenue Agency (CRA) received a complaint requesting that Tides Canada's charitable status to be revoked.

The group EthicalOil.org, headed up by a former Tory staffer, launched its complaint on Wednesday, telling CRA that Tides Canada gets around restrictions on political activities by funding "organizations that otherwise would have no access to charitable dollars because they are not registered charities."

Oliver held back from direct criticism of Tides, which is a multimillion-dollar clearinghouse for contributions - often from billionaire American foundations - used to fund dozens of environmental and social causes.

"There may or may not be an investigation by CRA of that organization as a result of a complaint," Oliver said.

The Tories' last budget included changes to make charities report the foreign funding they get for political activities and limit their ability to fund other charities' political activities.

Green Party Leader Elizabeth May slammed the changes as "a shot across the bow" of environmentalists in hopes they'll simply shut up.