The federal government must step up its efforts to counter the radicalization and recruitment of young Canadians by extremist Islamic groups, a Calgary imam said Friday.

And Syed Soharwardy said people who return from abroad after a stint with radicals in Syria or Iraq should be under a police microscope as soon as they land.

Soharwardy made the comments following a CBC report that identified Calgary brothers Collin and Gregory Gordon as two more young men who have recently left Canada to join Islamic fighters in Syria.

Not coincidentally, the spectre of homegrown terrorism was a dominant theme in the federal government’s annual national security report, released Friday by Public Safety Canada.

Terrorism remains the principal threat to national security, the report concludes, stressing the need to work with communities to counter insidious recruitment efforts on Canadian soil.

Soharwardy, who represents the groups Muslims Against Terrorism and the Islamic Supreme Council of Canada, welcomed the report’s conclusions, but chastised the government for falling short of the necessary effort.

“Early intervention is needed and the government has the resources and the tools to do that,” Soharwardy said.

“Communities, non-profit organizations, Muslims are working whatever they can with their own resources, but definitely it is the government role to support those activities.”

Canada’s intelligence agencies have failed in their responsibilities to ferret out these activities and should be shaken up, he added.

At the start of 2014, the government knew of more than 130 individuals who were abroad and suspected of terror-related activities, the report said. About 30 people with Canadian connections were suspected of terror activities in Syria.

“The government is aware of about 80 individuals who have returned to Canada after travel abroad for a variety of suspected terrorism-related purposes.”

Those latter people are the real threat, Soharwardy said. People coming home from places such as Syria and Iraq should be under close scrutiny.

“If they come back, the government has to watch them, be vigilant with them, inquire them. investigate them. These people will be coming from a combat environment, a very radical, very extremist, very violent environment and God forbid they may cause any serious problem to our society.

“That is my nightmare, that those who will come back will definitely cause problems, serious problems to the Muslim community in Canada as well as all Canadians.”

They must be held to account, he said.

“They should not be freely walking here and there, they should accountable for their actions.”

The spectre of homegrown terror has been top of mind in Canada and elsewhere around the world in recent months — notably Britain, which on Friday ratcheted up its national terror threat level to “severe,” the second-highest level, to indicate a terrorist attack is “highly likely.”

Intelligence and security services in the U.K. now believe around 500 Britons have gone to fight in Syria and potentially Iraq. Some of the plots are likely to involve fighters who have travelled from Britain and Europe to take part in fighting in the Middle East.

British police have appealed to the public to help identify aspiring terrorists after the killing of an American journalist focused attention on extremism in the U.K. The involvement of a person of British nationality in James Foley’s beheading underscored the need to identify those who might travel abroad to fight or are at risk of being radicalized.

In Canada, the government has tools to deal with Canadians who might be planning to wage terrorist attacks abroad. The Combating Terrorism Act, which came into force in July 2013, created new criminal offences for leaving or attempting to leave Canada for the purposes of committing certain terrorism offences abroad.

Soharwardy agreed with the report’s conclusion that al-Qaida remains a serious threat. But the splinter group now wreaking havoc in Iraq known as the Islamic State of Iraq and the Levant (ISIL) is a greater danger, he said.

“(ISIL) is a bigger threat, because they have been more successful in recruiting more westerners, more young people, more educated people.”

Public Safety Minister Steven Blaney said the report shows that the terror threat remains a priority for the federal government.

“It builds on an important dialogue we’ve begun with Canadians and serves to keep communities informed of this very real threat,” he said in a statement.