Fugitive US intelligence contractor Edward Snowden said on Tuesday there should be an international agreement on data collection to protect against the mass surveillance of citizens.
Speaking to the Council of Europe in Strasbourg via video link, he said a set of "common standards" would be needed to prevent widespread surveillance programmes like that carried out by the US National Security Agency.
The whistleblower, who lives in Moscow after being granted asylum by Russia, was speaking to officials from across Europe who are investigating mass surveillance.
"I believe the international community should agree to new common standards of behaviour, perhaps a Convention on mass surveillance," he told the council.
"We need to develop international standards to protect against the routine and substantial abuse of this technology, abuses that are ongoing today.
"This is not just a problem for the United States and the European Union: this is in fact a global problem", he said.
Snowden, now aged 30, said that the system developed by the NSA was used not just for the prevention of terrorism, but to "follow people, even for non-violent offences" and "without the issue of any judicial warrant".
Such monitoring "represents the most significant new threat to civil rights in modern times," he told the council.
The trove of documents leaked by Snowden sparked outrage in the United States and abroad about the vast capabilities of America's intelligence programs.
Following the revelations, President Barack Obama was forced to propose changes to the electronic surveillance of US citizens, including proposals put forward last month to take bulk phone data collection out of the hands of the NSA.
Although officials have defended the methods as necessary for national security, the scale of the NSA's surveillance sparked a wave of controversy on both sides of the Atlantic.
Separately on Tuesday, the European Court of Justice in Luxembourg ruled that the bloc's data-retention law governing phone calls and electronic data was illegal, saying in its current form it was disproportionate and overly-intrusive.
Snowden said that data had been used in Europe to "track, intercept and monitor the travel of innocent citizens, not suspected of anything".
Despite being exiled from his home country, Snowden said he was happy to have started a debate about online surveillance -- which he believes still has a long way to go.
"It's very difficult to achieve revolutionary change overnight, particularly on the topic of human rights," he said. "The key is we made incredible progress.
"Every citizen who had not even heard about these technologies is now talking about them," he said. "The fact that people are now aware... is worth everything that happened."