The RCMP have begun a review of reported heavier-than-usual trading in income trusts and dividend-paying stocks ahead of an announcement last week that the federal government was increasing the tax credit on corporate dividends.

NDP finance critic Judy Wasylycia-Leis sent a letter of complaint to the Royal Canadian Mounted Police earlier this week requesting the probe into whether Bay Street insiders received advance knowledge of the announcement, Staff Sgt. Paul Marsh told Bloomberg News.

"The RCMP will review the information provided to determine if there is a basis to proceed with a criminal investigation," Marsh said.

"It would be inappropriate to speculate what action may or may not be taken."

A forensic accountant told CTV Newsnet's Mike Duffy Live that he thinks the probability there was insider trading is between 75 and 85 per cent.

Either "someone had tremendous good luck ... or there's a leak," said Al Rosen.

But it isn't known where the leak may have occurred, he said, noting it could have occurred at any one of several areas within government.

"That's why I'm glad to hear the RCMP is going to look at it," he said.

During a campaign stop in Toronto, NDP Leader Jack Layton said he was pleased the RCMP was taking the complaint seriously.

"If it turns out that something untoward has happened here, that people were able to enrich themselves because of information, this should concern every Canadian," Layton said.

The NDP demand for a probe echoed similar requests by other opposition members.

The Conservatives have also called for the Ontario Securities Commission to investigate the matter.

But Ontario MPP Gerry Phillips, the minister responsible for overseeing the Ontario Securities Commission, rejected such a move on Tuesday.

"You're treading onto very dangerous ground if you're telling the OSC what cases it should investigate," he said in the legislature, saying it would be commensurate to political meddling.

Some stock market regulators are reviewing trading that took place ahead of Finance Minister Ralph Goodale's tax policy announcement, Doug Maybee, a spokesman at Market Regulation Services Inc., told The Globe and Mail.

"The markets did move prior to Mr. Goodale's announcement, there's no denying of that," he said.

"What caused the markets to move, that's something we're still looking into."

Goodale has denied allegations that the information may have leaked in advance to some investors.

He said no one should be surprised the stock markets surged in advance of his announcement.

Goodale said he made it clear an announcement would be coming before the opposition non-confidence vote, which took place Monday evening.

However, Rosen said most of the trading involved three brokers at most, and seemed to occur between 3:15 p.m. and 4 p.m. that day.

Bloomberg News cites some examples of heavy trading volumes:

The Yellow Pages Income Fund rose 3.4 per cent ahead of the announcement, in which Goodale said he wouldn't tax income trusts such as Yellow Pages.

The S&P/TSX Capped Income Trust Index climbed 1.5 per cent on Nov. 23, the day of Goodale's announcement, and jumped 4.4 per cent the next day.