Prime Minister Stephen Harper says Canadian officials are "reaching out" to their counterparts in Brazil over reports that Canada had used phone and email metadata to map communications of the South American country's Mines and Energy Ministry.

"The prime minister was very tight-lipped about the agency," the CBC's Terry Milewski reported Tuesday from Bali, where the prime minister is attending a summit of Asian leaders, but Harper said he was "very, very concerned" about the story.

Still, the prime minister didn't elaborate or indicate what if any explanation will be offered to Brazil.

Brazilian President Dilma Rousseff tweeted Monday that her country's Foreign Affairs Department would demand an explanation from Canada regarding the allegations, Reuters reported.

Brazilian Foreign Affairs Minister Luiz Alberto Figueiredo Machado summoned Jamal Khokhar, Canada's ambassador, to the country on Monday to explain the spying allegations, a Canadian official confirmed to CBC News.

The summons, a serious diplomatic measure, came the day after a Brazilian television report said the Communications Security Establishment Canada used phone and email metadata to map the communications of the Mines and Energy Ministry.

While Harper said Canada is reaching out to Brazilian officials, Milewski reported, "he wouldn't comment on, and I am quoting now, … 'national security operations.'"

Nor would he discuss what national security might have to do with any apparently industrial espionage in the Brazilian mining industry or ministry,

Harper did add that "we have a commissioner of the Canadian Security Establishment who audits the agency and the surveillance" to ensure they stay within Canadian law and that he will follow up, Milewski reported.