Expert: Snowden Leaks "Most Catastrophic Loss to British Intelligence Ever"

The Guardian planning to keep publishing leaks from the NSA whistleblower

Leaked surveillance programme details have been the "most catastrophic loss to British intelligence ever", a senior UK security expert has said.

Former No 10 adviser Sir David Omand said he assumed data leaked by ex-US intelligence worker Edward Snowden was being analysed by Russia and China.

He said the breach was worse than that by the Cambridge spy ring in the 1950s.