BBC: The number of terrorist plots in the UK is "mounting" and the "magnitude" of their ambitions growing, Met Police chief Sir Ian Blair has warned MPs.
He was making the case to the Commons Home Affairs committee for extending the current 28-day limit for detaining terror suspects without charge.
Terror law watchdog Lord Carlile told MPs longer detention would not harm relations between Muslims and police.
He said foreign policy was more likely to "radicalise young people".
The government has said the time has come to re-examine the 28-day limit - which was doubled from 14 days in 2005 - because of the complexity and nature of the threat of terrorism. Met chief warns over terror plots (more)
Mark Alexander
