Civil liberties groups have described the first public questioning of Britain's spy agency chiefs as disappointing and far from illuminating, saying the committee of MPs who quizzed the heads of MI5, MI6 and GCHQ failed to ask searching questions.

During the 90-minute intelligence and security committee hearing, MI5's Andrew Parker, the MI6 chief, Sir John Sawers, and Sir Iain Lobban, the director of GCHQ, were questioned on subjects including whether the agencies' interception of electronic communication was excessive, if there was a need for greater oversight of their work, and the effects of stories by the Guardian and others based on the revelations of Edward Snowden.

On the latter subject, Sawers said the Snowden stories had been very damaging and that "our adversaries are rubbing their hands with glee".

Shami Chakrabarti, the director of Liberty, said the promised inquisition had proved extremely tame. "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.

"Broad, friendly questions were easily batted away and little was said that isn't already on public record. A real inquiry into this grand breach of trust must now begin."

Nick Pickles, director of Big Brother Watch, contrasted the spy chiefs' reaction with the response to the Snowden revelations in other countries.

"As the US president, world leaders and international experts express concern about the scale of surveillance and the need to review the laws and policies involved, today was perhaps unique for the fact parliament found three people who think there is no need for reform."

His organisation has published a poll showing two-thirds of people believe the government should publish more data about the way surveillance powers are used.

Among omissions in the questioning, Pickles said, was explanations as to why Snowden was among 850,000 people with access to secret files, and the condemnation by Tim Berners-Lee, the internet's creator, of spy agencies' actions.

He said: "Many people will find it is surprising that the head of GCHQ was not even asked about how a 29-year-old contractor in Hawaii gained access to so much information about his organisation, or that the concerns of Sir Tim Berners-Lee about weakening encryption were not addressed in any meaningful way.

"Senior figures in the UK and US have all said that the Snowden revelations have not damaged national security, but the committee seemed uninterested in challenging the now familiar well rehearsed soundbites from officials.

"A public hearing is a welcome step towards long overdue transparency and a genuine debate about the legal framework is clearly in the public interest. However, on today's evidence there is still a long way to go."

Thomas Hughes, executive director of Article 19, said the hearing showed how any new public knowledge was being led by media reports.

"Without Snowden's revelations, the intelligence and security committee seemingly wouldn't have known the extent of the mass surveillance of our personal communications.

"Today's hearing has highlighted the need for the creation of a fully independent, effective and accountable oversight mechanism for the UK intelligence agencies."

A spokesman for the Open Rights Group said the committee had "failed to ask the difficult questions".

He said: "For instance, who decided that mass data trawling did not need an explicit parliamentary vote? How do they square data trawls with repeated human right judgments showing such harvests are going too far? Why is undermining internet security alright and why is it fine to break into potentially millions of accounts at Google and Yahoo! when there are legal routes to the same data?

"By concentrating on generalities the ISC failed to bite, which is extremely worrying as their main argument is that oversight makes us safe."