David Cameron accuses newspapers who make public the techniques used by spies, of “helping our enemies” and making it more difficult to maintain national safety.
The prime minister’s comments come as France and Germany seek bilateral talks with the US over revelations that intelligence was being gathered on European leaders.
At a press conference today Mr Cameron said Edward Snowden, and “to an extent” newspapers, were helping people avoid surveillance techniques.
He thanked the security services, saying that they do not often get public praise for the anonymous work they do.
He went on to highlight Britain’s close intelligence relationship with the US as part of the “five eyes” group, but added that he understands “what others (in the EU) want to do and very much support that, as will President Obama.”
Earlier, European leaders reacted with anger today at a European summit over revelations that the US National Security Agency monitored their telephone conversations.
The revelation provoked widespread condemnation, with the French and German governments demanding talks with the United States by the end of the year in an attempt to restore trust between the countries.
French President Francois Hollande has warned that “what is at stake is preserving our relations with the United States.
“They should not be changed because of what has happened. But trust has to be restored and reinforced.”
German Chancellor Angela Merkel added that “something must change – and significantly”.
“We will put all efforts into forging a joint understanding by the end of the year for the co-operation of the (intelligence) agencies between Germany and the US and France and the US, to create a framework for the co-operation.”
The allegations emerged from leaked document from the former US intelligence operative Edward Snowden.
The Guardian reported how a confidential memo shows the NSA encouraged senior officials in the White House, State Department and Pentagon to provide access to their contacts books, containing phone numbers of leading foreign politicians.
One US official alone is alleged to have passed on over 200 numbers, including 35 world leaders, who were immediately targeted for monitoring by the NSA.
In a carefully worded statement, the White House said the US is “not monitoring and will not monitor” Ms Merkel’s communications, but German officials pointed out that it did not deny monitoring the phone in the past.
The NSA memo obtained by the Guardian was dated October 2006 and issued to staff in the agency’s Signals Intelligence Directorate.
It describes how US officials mixing with world leaders and politicians could help agency surveillance: “In one recent case a US official provided NSA with 200 phone numbers to 35 world leaders.
“Despite the fact that the majority is probably available via open source, the PCs (intelligence production centres) have noted 43 previously unknown phone numbers. These numbers plus several others have been tasked.”
The document also describes how the numbers provided the NSA leads to further telephone numbers which were also targeted, but admits surveillance had produced “little reportable intelligence”.