Despite popular belief that they are chasing terrorists and master criminals, the world's spy agencies spend much of their time pursuing environmentalists, opposition leaders, dissidents and even airline staff, leaked documents show.

The intelligence agencies, including Canadian spies, are interested in civilian targets that go far beyond terrorism, according to the latest batch of South African intelligence agency reports, leaked to Al Jazeera. Many spy agencies are more preoccupied with political activists than with terrorism, the reports show.

One document revealed that the Canadian Security Intelligence Service (CSIS) was strongly interested in whether the Israeli airline, El Al, might have any gun-toting Israeli spies among its staff in international airports. It questioned whether El Al staff might have illegally obtained firearms.

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South Korea's spy agency wanted a "specific security assessment" of Greenpeace International's director, Kumi Naidoo, before the G20 summit in Seoul in 2010, while Cameroon's espionage agency sought an intelligence report on an opposition politician before an election in 2011. The Rwandan government wanted the authority to spy on "negationists" – anyone who questioned its version of the Rwandan genocide. And Sri Lanka wanted information on Tamils from Canada and elsewhere who were allegedly attending "military training" in South Africa.

South Africa rejected the requests from Cameroon, Rwanda and Sri Lanka, and it is unclear whether it spied on Mr. Naidoo. But another document showed that South Africa and Zimbabwe agreed to "monitor the activities" of environmental activists who were travelling to a global climate-change summit in Durban in 2011.

These environmentalists deserved "the attention of intelligence services" because they had a "potential for disruptive behaviour," the South African intelligence report said.

The same document said the South African and Zimbabwean agencies had agreed to spy on "rogue" organizations "engaged in subversive activities." But it failed to define "subversive" – leaving open the possibility of spying on legitimate anti-government groups.

Mr. Naidoo said he had always assumed that Greenpeace was under constant surveillance. But it was "numbing and chilling" to have it confirmed in the leaked documents, he told Al Jazeera on Tuesday.

The latest batch of leaked spy cables, released by Al Jazeera on Tuesday, are among a trove of documents that are described as the biggest leak of intelligence data since Edward Snowden released masses of secret information in 2013.

While foreign spy agencies were asking South Africa's security agency to crack down on political dissidents or environmental activists, South Africa itself was in danger of losing its secrets to foreign spies, the documents show.

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One 11-page document from 2009 gave a detailed list of the "security vulnerabilities" and "deficiencies" that were jeopardizing the South African government.

In one example, the document described how foreign intelligence agents were able to pose as diplomats and then gain "frequent" access to high-security installations, including nuclear sites. Delegations from Iran and China, among others, were able to use this tactic to "demand access to sensitive plants where advanced technology is being developed," the report said.

The document gave a long list of other official security weaknesses, including a lack of password protection on many government laptops. It also documented "hundreds of scams" by corrupt officials, which could allow security breaches.

Two days after the leaked documents were first disclosed, South Africa still had not commented on the leak by Tuesday night. Its State Security Agency promised a statement on Wednesday.

But analysts said the leak would be hugely damaging to South Africa's reputation in the intelligence community. "This leak will likely cause immense and potentially irreparable damage to the SSA [State Security Agency]," said Darren Olivier, a South African researcher, on the website of the African Defence Review on Tuesday.

"Not only are many of its own secrets and operations now compromised, but no foreign agency will feel safe in sharing sensitive information with the SSA any time soon. This may in turn harm South Africa's national security, cutting off the SSA's access to invaluable intelligence from other agencies."

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To regain the trust of other intelligence agencies, the South African government will need to find the source of the leak and make changes to prevent it happening again, he said.

David Maynier, an MP for the opposition Democratic Alliance, called on State Security Minister David Mahlobo to give an urgent briefing to a parliamentary committee on the leaked spy documents and whether any wrongdoing is involved in them. The leak is "likely to be the cause of considerable embarrassment to the State Security Agency," the MP said.

"We have never come this close to seeing inside the bottom drawers of the State Security Agency," he said.