TORONTO — The world's most expensive old masters painting could find its way into the collection of the Art Gallery of Ontario in Toronto if reports of the identity of its purchaser prove true.

The Massacre of the Innocents, painted in the early 17th century by the Flemish master Peter Paul Rubens, was sold at auction Wednesday in London, for about $117 million Cdn. That makes it the third most valuable painting ever sold at auction, after Van Gogh's Portrait of Dr. Gachet and Renoir's Au Moulin de la Galette.

A well-known London manuscripts dealer, Samuel Fogg, beat out seven other bidders in the 10-minute war for the oil, depicting King Herod's slaughter of Israel's newborns, as recorded in the New Testament. Fogg said he was not the buyer and would not who was.

However, a Canadian art collector who asked not to be identified and who is in the Sotheby's audience, said that David Thomson, a prominent Canadian art collector and the new chairman of Thomson Corp. was sitting next to Fogg.

"Thomson was the winning bidder, definitely," said the art collector.

No one in the art world is ruling out Thomson as the buyer of the painting, which, until this week's auction, had been in an Austrian monastery for 80 years and had been wrongly attributed to a Rubens associate.

Rubens, who died at 62 in 1640, rarely signed any of his works and had dozens of students and helpers.

The Thomson empire, of which Thomson assumed control in May from his father, Ken, has assets estimated at $30 billion and reported revenues last year of almost $12 billion.

At 44, the younger Thomson has amassed an eclectic art collection that includes 15th-century Flemish and German paintings, landscapes by John Constable, drawings by John Ruskin, an array of 19th-century photographs, pioneering expressionist works by Edvard Munch, originals by such artists as Picasso, Cy Twombly and Piet Mondrian, and even cartoons by Peanuts creator Charles Schulz.

What's intriguing art watchers is whether David Thomson, if he was the winning bidder, bought the Rubens for himself or on his father's behalf. Neither Thomson was available for comment.

Ken Thomson, whom Forbes magazine recently rated as one of the 15 wealthiest individuals in the world, has even greater fame as a collector than his son.

Upon his retirement at 78, the elder Thomson said he would be devoting a great deal of his time to his private art collection. It is well known that he is in negotiations with the Art Gallery of Ontario to donate some, most or perhaps all of his large collection to the gallery, including a Paul Kane painting that set a record in February this year for the most money ever paid for a Canadian work of art. It fetched $4.1 million.

The AGO was quiet about its possible receipt of the Rubens. However, an excited Christina Corsiglia, the gallery's curator of European art, said Thursday ``there isn't a museum anywhere in the world that wouldn't say, `What an addition!'''