The head of Canada's main spy watchdog says new rules — and possibly legislation — are needed to help keep an eye on federal intelligence agencies.

Chuck Strahl, chairman of the Security Intelligence Review Committee, says that as spy services work ever more closely together, there must be ways for watchdogs to do the same.

Strahl says he has no complaints about the review committee's ability to get information from the Canadian Security Intelligence Service, the agency he and fellow committee members monitor.

"The question though is, what about when it involves other government departments and agencies that we don't have access to?" Strahl said in a recent interview.

"Is the government satisfied that we can chase those threads when they disappear out of CSIS's hands?"

Strahl flagged the concern amid increasing calls for more comprehensive oversight of Canada's spy community, particularly in light of allegations about Communications Security Establishment Canada, the national eavesdropping agency.

Documents leaked by former U.S. intelligence contractor Edward Snowden suggest CSEC mounted a spy operation against Brazil's ministry of mines and energy and helped allies monitor leaders at a G20 summit.

Liberal bill would boost oversight

And although CSEC focuses on foreign intelligence gathering, it routinely assists CSIS with investigations. Liberal public safety critic Wayne Easter tabled a private member's bill in the House of Commons on Thursday to create a national security committee of parliamentarians that would have access to top-secret information — unlike existing committees of MPs and senators.

"The necessity of this legislation has been evident for more than a decade," Easter told a news conference.

Just last month, the NDP unsuccessfully sought support in the House of Commons to study stronger oversight for the intelligence community.

The Conservative government has said it is looking at an inter-agency review system that would modernize the current approach of spy watchdogs working in separate silos, but few details have emerged. Robert Decary, the recently retired commissioner of CSEC — a watchdog who reports to the defence minister — also expressed a desire to collaborate with the review committee over CSIS.

In citing a need for broader monitoring, Strahl points to the review committee's recent report on Abousfian Abdelrazik, a Montreal man who was imprisoned in Sudan.

The review committee, known as SIRC, was able to conclude that CSIS reported inaccurate and exaggerated information to partner agencies about Abdelrazik's case. However, it was unable to fully delve into the role played by the RCMP, Foreign Affairs, the Canada Border Services Agency and Transport Canada.

No authority to 'chase threads'

"We don't have the authority under the current system to chase those threads. All we can do is investigate CSIS," Strahl said.

"I hope the government is examining the legislative mandates of a review agency like SIRC, or like the office of the commissioner of CSEC, for example, and what it is that they are allowed to do and what you want them to do."

Strahl said intelligence agencies will continue to share more information with one another and work more closely on cases.

"Let's not just pretend it doesn't matter, because it will. And it'll increasingly matter, because the information sharing must continue and it must expand in my opinion — there's just no getting around it," he said. "That means we need those rules and perhaps legislation that reflects that 21st century reality."