Speaking Wednesday at a news conference, Mulcair denounced the reported attempt by Canada's electronic eavesdropping agency to monitor Brazil's Ministry of Mines and Energy as a big mistake
A Brazilian television report said the metadata — or indexing details — of phone calls and emails from and to the ministry were targeted by the Ottawa-based Communications Security Establishment Canada to map the ministry's communications.
Mulcair says it's further proof that the Conservatives have no ethical boundaries.
"This is a black eye for Canada. It's a huge mistake."
Prime Minister Stephen Harper has said he's very concerned" about the reports of spying, but the NDP leader sounded skeptical.
Harper "has been an abject failure in terms of his ability to deal with these ethical lapses," Mulcair said.
"He responds to nothing, claims he knows nothing about any of it, and yet it keeps coming out more and more."
The low-profile CSEC monitors foreign computer, satellite, radio and telephone traffic for intelligence of interest to Canada. Its staff of more than 2,000 includes experts in codebreaking, languages and data analysis.
In a rare address Wednesday to an Ottawa tech conference, CSEC chief John Forster was somewhat circumspect but clearly tried to dispel the recent flurry of allegations by noting a retired judge serves as watchdog over the spy service.
"Everything we do, and I mean everything we do, is reviewed by an independent CSE commissioner," Forster said.
"He and his office have full access to every record, every system and every staff member to ensure that we follow Canadian laws and respect Canadians' privacy."
Ironically, Forster warned about the threats to the Canadian government's computer networks from other nations, hacktivists, criminals and terrorists.
More than 100 nations possess the technology and financial resources to conduct persistent cyber-operations to collect intelligence or damage information infrastructure, he said.
The CSEC, with an annual budget of about $400 million, is a key member of the intelligence-sharing network known as the Five Eyes — Canada, the United States, Britain, Australia and New Zealand.
The National Security Agency, CSEC's American counterpart, is at the centre of a storm of leaks from former contractor Edward Snowden that document the U.S. agency's vast reach into cyberspace.
Snowden was also the source of documents detailing the alleged spying on Brazil.
Also on HuffPost