French nuclear power group Areva's purchase of Canadian uranium producer UraMin in 2007 for a high price was preceded by suspicious stock trades indicative of insider trading, a report said Saturday.

The controversial deal valued UraMin at more than $2.5 billion (1.89 billion euros) and was struck during peak demand for enriched uranium as nuclear energy was making a comeback amid concern over global warming and high oil prices.

Research conducted by La Presse de Montreal newspaper, however, said there was an unusually high volume of trades in UraMin shares in days leading up to the announcement of the Areva takeover.

Volume reportedly quadrupled, allowing well-informed investors to make a gain of 11-24 percent over four days, it said.

Areva is currently struggling to recover from a downturn in expectations for the nuclear power industry in the wake of the disaster at Japan's Fukushima Daiichi atomic plant last year, amid a management shake-up and big job losses.

The UraMin deal is at the center of a dispute involving Areva's former chief Anne Lauvergeon whose severance bonus was held back last year and as several inquiries scrutinize the circumstances surrounding the Canadian acquisition.

The possibility of insider trading has already been raised in an investigation commissioned by Areva, which had a 5.5 percent stake in UraMin prior to the takeover.

According to La Presse, on June 12, 2007 some 16.7 million UraMin shares changed hands, mostly in Toronto but also on the Alternative Investment Market (AIM) in London.

The timing was bad for Areva as the price for uranium had hit an all-time high of around $140 per pound. By the end of 2007, however, the price had fallen to $88 and is now around $52 per pound of material.

Areva announced a cash offer for $7.75 per UraMin share on June 15, 2007 and completed the purchase of the Canadian company six weeks later.