Sir Malcolm Rifkind, the chair of parliament's intelligence and security committee defends his decision to cancel the first televised cross-examination of the chiefs of the intelligence agencies saying the committee would have been only able to ask superficial questions about the information released by Edward Snowden, the former US National Security Agency whistleblower.

The committee was due to question the security agencies on camera . The decision to put them under public scrutiny this week had been hailed by the deputy prime minister, Nick Clegg, at his monthly press conference on Monday as proof that the intelligence agencies were accountable to democratic bodies. His remarks suggested the agencies would be, for the first time, asked to explain in broad terms how they responded to the allegations. Until now the government response has either been to say it will not comment on intelligence matters or that it is confident the agencies are acting within the law. Hours after Clegg's press conference, the ISC confirmed the session had been cancelled in the light of the Snowden allegations.

An unrepentant Rifkind defended the decision saying: "Our immediate priority is to do detailed work both on the intelligence aspects of the murder in Woolwich of Lee Rigby, and to examine the allegations against GCHQ arising out of the leaking of secrets by the American, Edward Snowden.

"To do that, seriously, requires us not just asking GCHQ and MI5 whether various allegations are true or false. We need to see any relevant reports, intercepts and other raw intelligence material. Most of this will be highly classified intelligence material." He said he found arguments that the public hearing should go ahead very unconvincing.

He said: "Any questions that we asked in public session, and the answers we received, would, of necessity, have been so general and superficial as to be of little public benefit. No doubt the Guardian would have then criticised us for such an inadequate investigation.

"Until now, the ISC has held all its evidence sessions in private. This has been crucial because the whole point of our work is to get access to, and examine not only the heads of the intelligence agencies but also to see their top secret files, documents, and intelligence raw material. It is obvious that such matters can only be dealt with in private session. Notwithstanding that, the ISC has decided, and obtained the agreement from MI5, MI6 and GCHQ to have an occasional evidence session in public, before the television cameras.

He continues: "We are determined that our public sessions with the intelligence chiefs will not be done for entertainment. They will not be occasions when we can carry out detailed investigations of specific allegations. That needs to involve access to secret information and that will continue to be done, as the public would expect, in secret."

His remarks suggest that the public sessions were never intended to be a detailed examination of specific activities of the agencies, but instead a broad brush discussion. He insisted the general public session will go ahead in the autumn.

He added: "One of the great dilemmas of a free and democratic society is how we reconcile preserving our liberty, with the need to allow our intelligence agencies to intercept our mail and tap our telephones. What is equally important, however, is to examine, constantly, how much information about the activities of the intelligence agencies can be shared with the public without harm to the legitimate needs of national security.

He adds: Just as the citizen's entitlement to privacy has to be balanced with the need to obtain secret intelligence to protect the citizen from terrorist attack; so ,too, we cannot escape the fact that secret information revealed to honest citizens will also be read and acted upon by terrorists and criminals. Getting the balance right is never easy but the ISC, with parliamentarians from all parties, has only the public interest in mind in the decisions it takes.