This photo shows Vineland Growers' Co-Operative, where a man bought about 1,600 kilograms of ammonium nitrate fertilizer two weeks ago. (Google Streetview)

Police in southern Ontario are reported to be searching for a man who bought what they consider to be a suspiciously large amount of fertilizer — enough, they say, to make a bomb.

The RCMP have confirmed to CBC News that a man purchased 65, 25-kilogram bags of ammonium nitrate fertilizer on May 26 at Vineland Growers' Co-Operative Ltd., in Lincoln, Ont., near St. Catharines in the Niagara Region.

According to a report by the QMI news agency, alerts have been sent to police forces across Ontario asking them to keep an eye out for the man. The RCMP say they are assisting with the investigation.

The 1,625 kg of ammonium nitrate is enough to make an explosive of the kind used by U.S. bomber Timothy McVeigh, QMI quoted the alert as saying.

McVeigh packed more than 1,000 kg of ammonium nitrate into a truck and exploded it at a federal government building in Oklahoma City in 1995. More than 160 people died in the attack.

The ammonium nitrate purchase comes as police and the military begin tightening security because of the upcoming G8 and G20 summits in Huntsville, Ont., and in Toronto.

The suspect has been described as a Caucasian man between 40 and 50 years old with a short, stocky build. He might also be missing fingers from his right hand.