The Leader-Post Norm Colhoun, owner of Skynorth Aviation in Lumsden, Sask., fuels a crop-duster. In June, a suspicious man approached him about a job flying such aircraft. Concern has been raised in the United States and Canada that terrorists could use crop-dusters for a germ warfare attack.

Investigators are probing at least two reports of Middle Eastern men who applied for work flying crop-dusters in Saskatchewan and asked suspicious questions about the range and carrying capacity of the planes.

Experts fear terrorists could use crop-dusters to spray chemical weapons or deadly infectious agents like anthrax or smallpox.

RCMP and CSIS officers interviewed the owner of a crop-dusting company in Lumsden, Sask., this week about an Arab man who approached the firm in June and asked detailed questions about aerial spraying.

And another crop-dusting company in Weyburn, Sask., also reported a strange request for work and training session from a man who identified himself as Iranian.

In the U.S., the FBI is investigating a visit by several Middle Eastern men -- including suspected hijacker Mohammed Atta -- to a crop-dusting company in Florida before the Sept. 11 attacks. Atta had also sought a U.S. Department of Agriculture loan for a crop-duster.

In Weyburn, a man of Middle Eastern descent spent a week in June at crop-duster Arndt-Air Ltd., hoping for a chance to fly one of the company's planes, according to pilot Richard Wayne.

Mr. Wayne said he knew the "peculiar" man only as "Sam" but said he was originally from Iran and was about 40 years old. He had recently spent time in the United States, Mr. Wayne said.

"I didn't mind helping him out. But he was totally strange."

Mr. Wayne says the man was particularly interested in the range and payload capacity of the aircraft.

He also wanted to train on the company's Ayers Thrush S2-600, a larger crop-duster that requires special certification to fly. The Thrush has a range of about 966 kilometres.

Although he claimed to be an experienced pilot, the man asked many rudimentary questions about flying and appeared to be a beginner when he tried to taxi one of the aircraft on the runway.

"He was having a whole bunch of troubles," Mr. Wayne recalls.

The man lived for about week in the pilots' quarters in the company hangar at the Weyburn airstrip.

"He wanted [his room] locked up at all times, like he was trying to hide something."

The man never flew the company's aircraft and left Weyburn after about a week, Mr. Wayne said.

Ron Arndt, the company's owner, said he has passed on information about the man to the RCMP.

In Lumsden, Sask., Skynorth Aviation owner Norm Colhoun says he was interviewed by RCMP and CSIS investigators about another pilot who had applied for crop-dusting work last June.

Mr. Colhoun said the man was in his early 30s and identified himself as "Mohammed Eslam."

The man claimed he had experience flying the Russian An-72 transport for the national airline, Aeroflot, Mr. Colhoun said.

"He was a reasonably pleasant gentleman," said Mr. Colhoun. "I gave him the courtesy of an interview but we weren't looking for pilots at the time."

Although Mr. Colhoun didn't give him a job, the man spent a lot of time with Skynorth's pilots, asking for details about their aircraft.

"Some of the questions he asked now raise suspicions," Mr. Colhoun said. "He asked about the range of the aircraft, the carrying capability, and how much fuel -- all [information] that's in the flight manual."

Two days after the terrorist attacks in the United States, Mr. Colhoun received an unusual e-mail inquiry about a crop-sprayer he had listed for sale.

The buyer listed Cambridge, Ont., as his business address and claimed to be in the crop-spraying business, but was not known to the industry group -- the Canadian Aerial Applicators Association.

Follow-up phone calls revealed the potential buyer had little knowledge of crop-spraying, Mr. Colhoun said.

The RCMP would not comment on what it called an ongoing investigation.

The Canadian Aerial Applicators Association last week warned its members to be on alert for potential terrorists. The note reports the U.S.'s National Agricultural Aviation Association was contacted by the FBI, which asked members to "be vigilant to any suspicious activity" related to crop-dusting.

As part of the ban on general aviation, crop-dusters in Canada were grounded after the Sept. 11 terrorist attacks but resumed flying two days later.