By Dominic Casciani
Counter-terrorism: Control orders have been highly controversial
Control orders used to monitor some terror suspects must not be abandoned as the move could damage UK security, a review of legislation has concluded.
Independent reviewer Lord Carlile said there were "no better means" of restricting some suspects' actions than the house arrest-like conditions.
But he said more minor suspects could have foreign travel bans instead.
The home secretary said control orders remained an important tool. They are currently in place against 12 people.
In total, they have been used against 45 people.
A number of terror suspects have been challenging the system since last June, when the Law Lords ordered the government to provide more information on the allegations against the suspects held under the restrictions.
At the time, there were widespread predictions that the system would collapse, but while the home secretary has lost some cases, a dozen control orders remain in force.
Lord Carlile said: "As the independent reviewer of terror legislation, it is my view and advice that abandoning the control orders system entirely would have a damaging effect on national security.
Cerie Bullivant, who was under a control order from 2006 to 2008
It tore apart my family life in a real sense initially. I had to move out of my mother's house, and I was a primary carer for her.
Then I had normal conditions of having to sign on at a police station every day, no travel, allowing police to search the property at any time. They control everything.
They're indefinite and you don't know why you're on them. You start analysing your life to see if anything could be misconstrued.
We later found one of the things they relied upon was a call to the terrorism hotline someone had made.
We worked out that was someone who hadn't seen me for over a year since my conversion [to Islam] and they were purely worried why would a young white man convert to be a Muslim.
"There is no better means of dealing with the serious and continuing risk posed by some individuals.
"I have considered whether control orders can or should be replaced by something else, or even renamed.
"I have been unable to find, or devise, a suitable alternative for the important residue of cases that cannot be dealt with by prosecution."
Lord Carlile, who met some of those under control orders as part of his review, said that he would have reached the same conclusions as the home secretary in each case that he had looked at from 2009.
But he said that the system needed improving and called for the government to think again about how it restricted the freedoms of those suspected only of wanting to travel abroad to fight.
In these cases, he recommended that control orders should be replaced by Travel Restriction Orders (TROs).
"To be clear, TROs are intended for the radicalised person whose first or early intentions are manifested by the desire to go for training and/or to act as an insurgent," he said.
Lord Carlile said that he supported the idea of a special "watch list" that could be used to prevent people from leaving the country.
The government is examining how watch lists work in the wake of the alleged failed attempt to bomb an airliner heading to Detroit in December.
Home Secretary Alan Johnson said control orders, created under the Prevention of Terrorism Act 2005, remained an important tool and he would respond in full to the Carlile report.
He said: "I believe [the Act] continues to strike the right balance between protecting the public and safeguarding the rights of the individual, which is why I am asking Parliament to renew the Act."
The Home Office has revealed the government has spent more than £8m on legal fees trying to maintain the control order regime.