MI6 chief Sir John Sawers said the leaks from NSA whistleblower Edward Snowden "have been damaging and put operations at risk."
Al-Qaeda is "lapping up" the leaks and Britain's enemies are rubbing their hands with glee, the British intelligence chief added.
More top news
Zimbabwe's recently fired vice president is set to return to the country be sworn in as the new president.
The US-led UN Command has released footage of a North Korean soldier's dramatic escape and shooting in the demilitarised zone.
Eight of those who were on board have been found by a search and rescue operation near the coast of Japan.