Prime Minister Stephen Harper says he’s "very concerned" about reports that Communications Security Establishment Canada has spied on Brazil’s ministry of mines and energy.

Speaking in Indonesia, where he was attending the Asia-Pacific Economic Cooperation summit, Harper said Canadian officials are “reaching out” to their Brazilian counterparts.

Brazilian President Dilma Rousseff summoned the Canadian ambassador Monday, the day after an investigative news program reported that spies from CSEC had accessed communications within Brazil’s mines and energy ministry.

Rousseff expressed her outrage on Twitter, saying that espionage is “unacceptable among countries that claim to be partners.”

The report from Brazil’s Globo TV was based on documents leaked by former U.S. National Security Agency contractor Edward Snowden. Journalist Glenn Greenwald, who has been reporting on Snowden’s leaks and the NSA for months, worked with Globo to produce the report.

A spokesperson for the Communications Security Establishment Canada said the agency “does not comment on foreign intelligence gathering activities.”

The CSEC also said that it cannot target Canadians under the law.

Harper said his government will be doing “appropriate follow-up” on the matter. He said there is a commissioner at the CSEC whose job it is to ensure the agency operates under Canadian law.

The Globo TV report did not say whether Canadian spies read emails or listened to phone calls at the Brazilian ministry.

Some experts say the allegations of espionage are not surprising in light of Canada’s economic interests in Brazil. But many expressed surprise that Ottawa would risk damaging the diplomatic and trade relationship with the South American country.

Relations between Brazil and the U.S. are already strained because of revelations that the NSA spied on Brazilian communications.

Rousseff has cancelled plans for a state visit to Washington this month.

Liberal Leader Justin Trudeau said Tuesday his party will introduce legislation next week that, if passed, would allow for parliamentary committee oversight over national security activities.

“The committee would be subjected to rules that would allow it to ensure that our security agencies are protecting us without abusing their powers,” he said.

Harper should have known what the CSEC had been doing, Trudeau said.

“This is a prime minister who controls everything -- whether it’s in his office or his government,” he said. “If it’s true that he didn’t know what was going on, that’s disappointing. That suggests a lack of supervision of our agencies.”

With files from The Canadian Press