MPs have warned that the preparations for the London Olympics have put the intelligence and security agencies under "unprecedented pressure."
The parliamentary Intelligence and Security Committee (ISC) - which oversees the work of MI5, MI6 and GCHQ - expressed concern that risks were been taken with other aspects of security because of the demands of the Olympics.
Staff have been taken off lower priority areas of work so that they can concentrate on the potential threat to the Games.
More top news
Tributes have been left in Caledonian Road in Islington where 15-year-old Alan Cartwright died after he was stabbed.
A boy has died after he and his friends were attacked while cycling in north London.
Three police officers have been praised for their actions in helping a four-year-old boy who had become stuck on a roof in Newham.