Woolwich: Police 'should answer questions'
24 May 2013 Last updated at 09:12 BST
The actions of the security services are to be investigated, after it emerged that the two men arrested over the murder of a soldier in Woolwich on Wednesday were both known to MI5.
Drummer Lee Rigby, who was 25 and from Manchester, was killed by suspected Islamist extremists wielding knives and a meat cleaver. MPs and peers will examine what information existed about the men.
Ian Blair, former commissioner of the Metropolitan Police, told the Today programme's John Humphrys that "the security forces have limited resources" and that "they must prioritise people who are most likely to move from being interested in violent extremist to carrying it out".
He said that the security forces "have to have very high levels of suspicion before [they] can put surveillance on".
He went on to call for someone to answer questions: "It's important for the public to have somebody say within the limits of legality that either something was mistaken - either decisions were badly taken or they weren't - because I think it's important for the public to know that security services and the police are operating properly."
First broadcast on the Today programme on Friday 24 May.