London, United Kingdom - An unprecedented public appearance by British spy chiefs has been lambasted by campaigners for civil liberties and privacy. The directors of the three main UK intelligence agencies were facing questions over the conduct of their organisations following revelations about British complicity in mass internet surveillance.

Thursday's televised session of the intelligence and security committee, the parliamentary panel that oversees the activities of the British secret services, was hailed by former defence minister Malcolm Rifkind, the committee's chairman, as "a very significant step forward in the transparency of our intelligence agencies".

It marked the first time the heads of MI5, the UK's domestic security agency; MI6, which collects foreign intelligence; and GCHQ, a communications intelligence-gathering hub; had been subjected to questioning by parliamentarians in public view, albeit with the caveat that they would not be asked to reveal "secret information" and with the safety net of a two-minute live delay.

But Kenneth Page, a policy officer for campaign group Privacy International, said that efforts to talk up the hearing as a "historic public grilling" were wide of the mark as the chiefs used the occasion instead to turn their fire on journalists who had published stories based on leaked documents acquired from the US whistleblower Edward Snowden.

"It was tame, predictable, and limp. The committee was almost fawning in their attitude and showed a near sense of embarrassment at having to hold them to account in public at all," Page said in a statement sent to Al Jazeera.

Iain Lobban, the director of GCHQ, whose organisation's activities have faced the most scrutiny since details of its Tempora internet monitoring operation were exposed by the UK's Guardian newspaper in June, told the committee he could cite evidence of terrorist groups that had changed the way they communicated as a direct consequence of the story.

"The cumulative effect of the media coverage, the global media coverage, will make the job that we have far, far harder for years to come," Lobban told the committee.

Assessing the terrorism threat faced by the UK, Andrew Parker, the director general of MI5, said 34 plots had been disrupted since the 2005 London bombings killed 52 people, and praised the "fantastic work" done by GCHQ to detect terrorist communications.

"That leads to us finding terrorist plots that we would not otherwise find, that we are then able to thwart, which leads to lives being saved. There are real instances of that, including this year," Parker said.

And in one of the sharpest moments of the session, John Sawers, the head of MI6, questioned whether journalists were in a position to make judgments about whether leaked material posed a threat to national security.

"What I can tell you is that the leaks from Snowden have been very damaging. They have put our operations at risk," he said. "It is clear that our adversaries are rubbing their hands with glee. Al-Qaeda is lapping it up and our own security has suffered as a consequence."

Not a 'grilling'

From the intelligence agency perspective, it couldn't have gone better. From the public's perspective, little was accomplished or revealed. Kenneth Page, Privacy International

But Page said the intelligence chiefs had escaped largely unchallenged on broader issues such as the legality of the Tempora surveillance programme and the sharing of data gathered from it with the US' National Security Agency, for whom Snowden worked as a contractor.

"From the intelligence agency perspective, it couldn't have gone better. From the public's perspective, little was accomplished or revealed. This was no grilling. This was not scrutiny," he said.

That view was echoed by Shami Chakrabati, director of civil liberties campaign group Liberty, who said the committee had failed to address key public concerns, with members restricting themselves to "broad, friendly questions that were easily batted away".

"These public servants presided over blanket surveillance of the entire population without public, parliamentary or democratic mandate. Yet they faced a grilling that wouldn't have scared a puppy," she said.

Speaking to Al Jazeera after the hearing, former Liberal Democrat leader Menzies Campbell, a member of the intelligence and security committee, conceded that further debate was needed about the legal framework within which the security services operated.

"It's not just a question of what the agencies find out. It's a question of what we think as a nation has to be kept secret," he said.

A step towards transparency?

But Charlie Edwards, an expert in national security at the Royal United Services Institute think tank, told Al Jazeera that the session, coupled with a parliamentary debate last week on surveillance concerns, still marked a significant step forward in holding the intelligence agencies to account.

In terms of educating the public and informing them about what the service chiefs do, and what their concerns are in terms of terrorism and cyber-security, I think it's a watershed moment. Charlie Edwards, RUSI

"I think the committee and the agency chiefs could have done a better job but it was a pretty good first effort, and we know that when they go into private committee there will be some harder questions," he said.

"In terms of educating the public and informing them about what the service chiefs do, and what their concerns are in terms of terrorism and cyber-security, I think it's a watershed moment. This is the beginning of a really robust accountability and oversight process that will look deep into what the agencies do."

In an editorial published on Friday, the Guardian, which has been sternly criticised by the British government over its collaboration with Snowden, acknowledged that the hearing had been "a step in the right direction".

But, the editorial added, it had "skated over any serious questioning about complex issues to do with mass surveillance, civil liberties or privacy", delivering instead "a gentle 90 minutes of polite questioning in which little was demanded or gleaned".

And the newspaper offered a robust defence of its handling of the documents leaked by Snowden, describing their loss as "plainly damaging" for western intelligence.

"The intelligence agencies were saved from true catastrophe by only one thing: the fact that Snowden didn't dump the material on to the web, but handed it instead to journalists. Together with the New York Times and Washington Post, we have worked carefully and responsibly to disclose a small proportion of what he leaked.

"Some would like newspapers gagged or prosecuted. Be careful what you wish for. Kick newspapers by all means, but, without them, be prepared for something much worse."

Follow Simon Hooper on Twitter: @HooperAJ