Foreign interference continues to pose a threat to Canada's sovereignty and national security, the head of CSIS says in a confidential report.

CSIS director Richard Fadden writes that those targeted by foreign agencies may be subject to threats, coercion or potential blackmail. (Adrian Wyld/Canadian Press)

"These clandestine efforts by foreign governments to influence our officials, policies and communities have the potential to undermine our ability to make independent decisions in Canada's national interests," CSIS director Richard Fadden wrote in a report to Public Safety Minister Vic Toews.

Fadden also writes in the heavily censored report, obtained by The Canadian Press, that those targeted may be "subject to threats, coercion or potential blackmail."

Fadden wrote the report following his interview in July with CBC News. Fadden had told the CBC that foreign governments hold influence over at least two cabinet ministers in two provinces, and are also involved with municipal politicians in B.C. and federal public servants.

He did not provide any names, but implied that China was one of those foreign governments.

Fadden also appeared before the House of Commons public safety and national security committee to answer questions about his comments.

The report censors the names of specific countries, provinces and individuals.

"Politicians are targeted to solicit support for policies and positions that favour the interests of the foreign state or entity," Fadden wrote.

The influence comes in the form of electoral support, he writes.

Fadden writes that the influence on politicians and public servants can be subtle and involve a long period of cultivation.

"It is a slow and methodical development of relationships that aim to affect the perspective and decision-making of those being influenced," he writes.

Fadden writes that the investigation of foreign interference presents "several challenges" to CSIS, which includes distinguishing between foreign interference and legitimate lobbying.

But he concludes that the "manipulation of Canada's government and ethno-cultural communities through foreign interference poses an ongoing threat to our sovereignty and national security."

With files from The Canadian Press