OTTAWA -- Canada's border agency has flagged the possibility of Iranians with "sinister motives" slipping into the country -- a warning that came in the months leading to the arrest of two men charged with plotting to attack a Via Rail train with help from al Qaeda in Iran.

An intelligence report by the Canada Border Services Agency said 19 Iranian nationals had been found inadmissible to Canada on security grounds since 2008 -- the majority of them refugee claimants lacking proper documentation.

The July 2012 report, Irregular Migration of Iranians to Canada, was obtained by The Canadian Press under the Access to Information Act.

"Iran is the number one source country of improperly documented migrants who make refugee claims in Canada," says the report, portions of which remain secret.

"Most of these migrants cite persecution based on religion, political opinion and sexual orientation."

A significant percentage of the arrivals use "facilitators" to enter Canada, adds the report.

"Information provided by the migrants on their smugglers suggests possible links to organized criminal elements both within and outside of Canada."

The border agency cites the June 2012 conviction of a man for smuggling two Iranians to Vancouver from China using phoney Israeli passports.

Many people seeking refuge in Canada use fake documents and rely on middlemen to help them flee persecution in their homelands.

In addition, the number of Iranians making refugee claims in Canada is relatively small -- about 300 a year -- and in 2011 more than 85 per cent were granted asylum, the report says.

However, the manner in which they arrive and the possible links to organized crime "are of concern," the border agency adds.

"While Iranian irregular migrants mainly enter Canada to make refugee claims, it is possible that certain individuals may enter with more sinister motives."

The 19 Iranians denied haven in Canada for security reasons were deemed inadmissible under a provision of the Immigration and Refugee Protection Act covering terrorism, subversion and espionage.

Iranian links to Islamic extremism came to the fore this week with the arrest of two men accused of scheming to derail a passenger train in southern Ontario.

Raed Jaser, 35, of Toronto, and Chiheb Esseghaier, 30, of Montreal, face terrorism-related charges in what the RCMP says was a plot guided by elements of the al-Qaida organization in Iran.

The Mounties have not elaborated on the foreign connection, saying only that the support did not come from the Iranian government.

The border services agency report notes recent American concerns about Iranian secret operatives and members of the Hezbollah extremist group, backed by Iran, carrying out attacks in the United States. Testimony in March of last year before the U.S. House Committee on Homeland Security alleged Hezbollah was active in stealing and forging high-quality passports that could allow members to travel freely.

Hezbollah was added to Canada's list of terrorist entities in December 2002. The assets of any listed group may be seized. In addition, it is a crime to knowingly participate in the activities of a designated organization or deal in its property or finances.

In late 2010 it emerged through online document leaker WikiLeaks that the Canadian Security Intelligence Service had responded to hints of possible terror operations by "vigorously harassing" known members of Hezbollah.