The Conservatives say it is "a nonsense" to describe the latest absconded terror suspect as being no threat to the public.
Patrick Mercer has criticised the government's control orders
The man, a British national, was the third to disappear while under a control order, which imposes a type of house arrest on terror suspects.
The individual absconded earlier this month, Home Secretary John Reid said.
Tory homeland security spokesman Patrick Mercer said those who abscond have to be regarded as "dangerous".
The orders were brought in for cases where there was not enough evidence to bring suspects to trial.
Mr Mercer said: "The Home Office coming up and saying, you know, it's not so bad, this guy, whoever he is, he's not much of a threat.
"But surely we were told he was radicalised and had prospects of going overseas to carry out jihad.
"You can't have a bloke on a control order and when he absconds say well, he wasn't that dangerous really."
Mr Reid said there were 18 control orders currently in force.
Two men - a British citizen and an Iraqi - who absconded at the end of last year are still at large, the statement confirmed.
In the latest case, the suspect absconded shortly after being served with a control order.
Mr Reid said: "The control order was designed to address the risk posed by an individual who had recently been radicalised and wanted to travel abroad for terrorism-related purposes.
"Obligations included a requirement to report daily to a police station, to surrender travel documents and to reside at a specified address.
"The individual is not believed to represent a direct threat to the public in the UK at this time."
Mr Reid said public safety was the "top priority" for the police and government.
He said police were trying to track down the suspect and "an anonymity order is in place".
After consulting the police, the government is not seeking to overturn the order, added Mr Reid.
A Home Office spokesman said: "Control orders are essential where it is not possible to prosecute individuals for terrorism-related activity and, in the case of foreign nationals, where they cannot be removed from the UK.
"However, we have always made clear that control orders were introduced as a next best alternative for dealing with suspected terrorists.
"We have sought stronger controls to deal with suspected terrorists who cannot be prosecuted, but have been prevented by Parliament and the courts."
Liberal Democrat home affairs spokesman Nick Clegg said a "wholesale review" was needed.
"Control orders were the centrepiece of the government's anti-terrorist strategy," he said.
"There must now be a wholesale review of their effectiveness as part of the long-promised overhaul of anti-terror laws."