Image caption Edward Snowden has some 58,000 GCHQ files

Guardian editor Alan Rusbridger says he plans to publish more revelations from Edward Snowden despite MI5 warning that such disclosures cause enormous damage.

Mr Rusbridger insisted the paper was right to publish files leaked by the US intelligence analyst and had helped to prompt a necessary and overdue debate.

His comments come after criticism from the new head of MI5, Andrew Parker.

Making public the "reach and limits" of intelligence-gathering techniques gave terrorists the advantage, he said.

Mr Snowden, a former CIA contractor, fled to Russia with a wealth of secret data including some 58,000 files from GCHQ, Britain's electronic eavesdropping agency.

The stories that followed in the Guardian newspaper, based on material provided by Mr Snowden, revealed the huge capacity of British and US intelligence agencies - GCHQ and NSA - to monitor communications.

Mr Rusbridger said more stories would be published in the future as the leaked documents were "slowly and responsibly" worked through.

If Parliament's not going to have this discussion and if the courts can only do this in private then I think absolutely it falls to the press to stimulate a discussion Alan Rusbridger, Guardian editor

In his first public speech since his appointment to director general in April, Mr Parker said intelligence gathered by GCHQ had played a vital role in stopping many UK terrorist plots over the past decade.

Without mentioning Mr Snowden by name, he said ''it causes enormous damage to make public the reach and limits of GCHQ techniques".

He warned that terrorists now had tens of thousands of means of communication "through e-mail, IP telephony, in-game communication, social networking, chat rooms, anonymising services and a myriad of mobile apps".

Mr Parker said it was vital for MI5 to retain the capability to access such information if it was to protect the country.

Mr Rusbridger said those on the security side of the argument wanted to keep everything secret and did not want a debate.

"You don't want the press or anyone else writing about it. But MI5 cannot be the only voice in the debate," he told BBC Radio 4's World at One.

He added that his newspaper had revealed the "extent to which entire populations are now being potentially put under surveillance".

"I just spent a week in America where everybody is talking about this, from the president down."

Media playback is unsupported on your device Media caption Guardian editor Alan Rusbridger says some intelligence leaks should remain unpublished.

He added: "It's quite surprising to me that the number of MPs in this country who have said anything at all in the last four months can be counted on one hand - Malcolm Rifkind, Tom Watson, David Davis.

"So, if Parliament's not going to have this discussion and if the courts can only do this in private then I think absolutely it falls to the press to stimulate a discussion, which as I say, throughout America, throughout Europe, is one that the public are intensely interested in."

Asked about Mr Parker's suggestion that publishing the documents was helping terrorists, Mr Rusbridger said: "They will always say that. You read histories of intelligence and you go back to the 1990s and the security people were saying the same."

The independent MP Patrick Mercer said intelligence data should not be published if it compromised public security.

"If in any way our security is compromised by revealing too much, that's a mistake. Just imagine if we had revealed the whole Enigma secret during the Second World War.

"That might have been in the public's interest - but we'd have lost the war."