The Guardian has published just one percent of the material it received from former National Security Agency contractor Edward Snowden, its editor said, as he denied the newspaper had put lives or national security at risk.
As he was grilled by politicians on Parliament's home affairs committee on Tuesday, Alan Rusbridger accused British authorities of trying to intimidate the newspaper and warned of national security being used as a trump card to stifle debate.
The Guardian helped spark a global debate on privacy and security by publishing a series of stories based on leaks from Snowden disclosing the scale of telephone and internet surveillance by spy agencies in the US and Britain.
Rusbridger said the leak amounted to about 58,000 files, and the newspaper had published about one percent of the total.
Government and intelligence officials have reacted angrily to the leaks and said they compromised British security and aided terrorists.
Britain's top three spy chiefs said last month that al-Qaeda and other terror groups were "rubbing their hands in glee'' in the wake of Snowden's leaks.
We're not going to be put off by intimidation, but nor are we going to behave recklessly
Several Conservative politicians have said The Guardian should be prosecuted for breaching terrorism laws.
Rusbridger defended the newspaper's decision to publish the secret material.
He said stories published by The Guardian, The Washington Post and others had prompted much-needed debate about the scale of intelligence activities and exposed the limits of regulatory laws drawn up in the pre-Internet era.
"There is no doubt in my mind that newspapers have done something that oversight has failed to do," he said.
Questioning by members of the all-party committee ranged from supportive to hostile, a sign of how deeply opinion is divided on the issue.
Conservative politician Michael Ellis asked whether The Guardian would have passed information to the Nazis during World War II, while the committee's Labour chairman, Keith Vaz, asked Rusbridger whether he loved his country.
"I'm slightly surprised to be asked the question,'' Rusbridger said.
"But yes we are patriots, and one of the things we are patriotic about is the nature of democracy and the nature of a free press.''
Rusbridger denied placing intelligence agents at risk and said his newspaper had made very selective judgements about what to publish and had not revealed any names.
British police launched a criminal investigation into the leaks after detaining the partner of Glenn Greenwald, then a journalist with The Guardian, at Heathrow Airport in August under anti-terrorism legislation.
Rusbridger said he did not know whether his newspaper was being investigated by police.
He said the publication had come under pressure from authorities in a way that would be inconceivable' in the US, where journalists can rely on First Amendment protections of freedom of speech.
He cited pressure to stop the stories from Britain's top civil servant, politicians' calls for the newspaper to be prosecuted and a security agency threat to confiscate The Guardian's hard drives containing Snowden files.
"I feel that some of this activity has been designed to intimidate the Guardian,'' Rusbridger said.
He said the newspaper would continue to publish responsibly.
"We're not going to be put off by intimidation, but nor are we going to behave recklessly,'' he said.