OTTAWA (AFP) - Canada's electronic eavesdropping agency chief spoke for the first time on Wednesday since allegations of spying on Brazil's mining and energy ministry, saying its work is legal and doesn't target Canadians.

Mr John Forster, head of the Communications Security Establishment Canada (CSE), was speaking at a technology conference in Ottawa, after Brazilian TV station Globo said on Sunday that the agency carried out industrial espionage against Brazil's government.

The report was based on documents leaked by former United States (US) intelligence contractor Edward Snowden.

"I can tell you that we do not target Canadians at home or abroad in our foreign intelligence activities, nor do we target anyone in Canada. In fact, it's prohibited by law. Protecting the privacy of Canadians is our most important principle," he said.

He noted the uproar in the media over the CSE's mandated foreign signals intelligence activities.

But he added: "Because of the classified nature of our work, I am sure you can appreciate that I can't say much.

"Everything that CSE does in terms of foreign intelligence follows Canadian law."

Globo cited leaked documents showing a detailed outline of the Brazilian ministry's communications including phone calls, email and Internet traffic.

Mr Snowden, a 30-year-old former NSA contractor who has sought refuge in Russia, is wanted by the US after revealing details of the agency's massive snooping activities.

Canadian Prime Minister Stephen Harper on Tuesday said he was "very, very concerned" about the allegations, but said an independent commissioner oversees the CSE's activities to ensure compliance with Canadian laws.