Underlining Tory concern at Mr Blair's confidence on the law- and-order portfolio, Mr Clarke warned people not to trust the 'new mood music' from Labour on crime.
'I wonder whether the police much trust a shadow Home Secretary of a party which has such an appalling record on law and order and support for our police forces,' Mr Clarke told the Conservative western area conference in Weston-super-Mare.
'I accept that Labour abhor terrorist violence as much as we do. Their problem is that they don't know how to tackle it properly.'
Mr Clarke said the public was 'genuinely mystified' about the changes Mr Blair proposed to the Prevention of Terrorism Act, which Labour voted against, when it was renewed on Wednesday in the Commons.
Mr Blair had called for a judge, rather than the Home Secretary, to review police requests for terrorist suspects to be held for more than four days, and for exclusion orders to be scrapped.
'What were they trying to get out of it? More civil rights for potential terrorists? Their message was not so much 'troops out' as 'terrorists in',' Mr Clarke said.
Outlining plans for tougher action on juvenile crime, the Home Secretary criticised Mr Blair for refusing to support his proposal to deal with persistent young offenders by providing custodial powers for the courts to lock up 12 to 15- year-olds in new training centres.
A Labour spokesman responded by saying: 'Mr Clarke is obviously rattled by Mr Blair's performance.'
Mr Blair, who is calling for more local authority secure places, last night accused the Government of providing resources for only three additional places, in spite of a promise two years ago to build an extra 65.
Mr Blair said Government had also cut local authority residential places for the most disturbed and vulnerable young people. He said the number of local authority residential homes had fallen from 1,130 in 1989 to 950 last year, a loss of 180 homes with 1,650 beds.Reuse content