Canada Revenue Agency officers, backed up by police, raided locations in three provinces Wednesday as part of a criminal tax-evasion probe stemming from the Panama Papers, the agency said.

About 30 criminal investigators from the CRA executed three search warrants in the Toronto area, Calgary and West Vancouver, with assistance from the RCMP and the West Vancouver police, the CRA said in a statement online.

It's the first time the revenue agency has publicly disclosed details of any of the "several criminal investigations" it has long said it is conducting based on the Panama Papers leak, and could be a sign the CRA is preparing to bring rare criminal charges against people hiding money offshore.

"The CRA's investigation identified a series of transactions involving foreign corporations and several transfers through offshore bank accounts used, allegedly, to evade taxes," the agency said.

The CRA did not identify which people, businesses or locations were targeted. Spokespeople for the agency and for Revenue Minister Diane Lebouthillier would not provide further information about Wednesday's raids.

West Vancouver police confirmed two of its officers were involved in executing a search warrant there, in a supporting role to CRA agents. The force would not divulge any further details.

Glen Jennings, a Toronto defence lawyer specializing in white collar crime, said there's a good chance that tax-evasion charges will ensue.

"Anecdotally, you would think most of those cases that result in search warrants ultimately result in criminal charges being laid," he said.

Senator Percy Downe has long denounced what he sees as a two-tiered tax enforcement system, where domestic evasion is firmly cracked down on while offshore schemes get 'kid-glove treatment.' (CBC)

The Panama Papers leak was revealed in April 2016 by a global consortium of media outlets, including the CBC and the Toronto Star in Canada, and a month later the CRA obtained all the records through official channels.

Last month, CBC News reported that while a dozen governments around the world say they've recovered a combined $500 million in unpaid taxes so far thanks to the huge leak of financial records, the CRA has so far not collected a penny.

The stark contrast fuelled continuing criticism of the CRA's effectiveness at catching offshore tax cheats. CBC News has previously reported that few, if any, of the criminal convictions the agency cites in defence of its record actually have anything to do with offshore tax evasion.

The CRA has said numerous times that it is criminally investigating possible tax cheating revealed in the Panama Papers, and that it has executed an unspecified number of search warrants going back as far as summer 2016.

CBC News has repeatedly pressed for the details of those search warrants, which are public court documents, in order to verify the CRA's claims. But the agency, citing taxpayer privacy, previously refused to disclose anything about them — including even basic information like how many there were or what cities the searches were conducted in.

"The CRA over the years has not been doing a very good job at explaining to Canadians what they're doing and why they're doing it," said Sen. Percy Downe, a member of the Senate Liberal caucus, who for years has lambasted the CRA's approach to ferreting out offshore tax cheats.

"Any effort they're making to be more transparent in their activities is obviously welcome."