Judges should be able to decide how long alleged terrorists can be detained without trial, a Government adviser said yesterday. Lord Carlile QC, the independent reviewer of counter-terror laws, said the continuing row over the right number of days to hold a suspect was ''completely sterile''.
He suggested MPs should give up the power to set a limit and hand it over to the judiciary.
Lord Carlile spoke out after a weekend of confusion over Government plans and police demands.
Ministers have already announced that they will consult about the prospect of increasing the 28-day limit.
They do not want to risk another Commons defeat as occurred when they pressed for 90 days. At the weekend, Ken Jones, the head of the Association of Chief Police Officers, appeared to suggest that suspects should be held indefinitely.
Yesterday, Lord West, the new security minister, said he backed an extension of the 28-day limit because Islamist gangs in the UK posed "a real threat to this nation".
Lord West, a former chief of defence intelligence, told the BBC Radio 4 Today programme: "I have come back to this after about 16 months away from it and I have to say I was quite concerned when I saw what the level of threat is.
"If one looks at what our security service and police are looking at on a day-to-day basis, they are now monitoring over 200 groupings or networks which to varying degrees are threatening our security.
"The scale of this whole thing is quite dramatic."
He added: ''Looking at the complexity of this, there will be occasions when we need more than 28 days. How we exactly do that is something that I hope we can come to some sort of consensus on."
However, Lord Carlile said it would be better to give judges the power to monitor detention periods in individual cases.
Suspects' rights would be "paramount" and detainees would have the right to appeal against continued custody. He expected only a handful of individuals to be held for more than two or three weeks under such a regime.
He said: "What Parliament should do is put this in the hands of senior judges, who have a great deal of experience in analysing evidence."
He added: "The fact is that the debate on days is completely sterile. I would have thought that every civil liberties organisation in this country and every person detained would be happy for their case to be considered by a senior judge on an evidence basis.''
Police say they are "up against the buffers" when they question suspects against the 28-day limit. However, it is longer than in any other country and four times lengthier than it was three years ago.
David Davis, the shadow home secretary, said not "one shred of evidence" had been presented that demonstrated the need to extend the limit.