Control orders are part of the anti-terrorism effort

Mr Blair was responding to the Tories' criticism that the men absconded - one through the window of a mental health unit - due to "incompetence".

He said he would have preferred tougher terrorism laws, but had been blocked by opponents in Parliament and the courts.

"Control orders were never going to be as effective as detention," he said at his monthly media conference.

"But of course, we've got to make sure that if someone breaches their control order, then they're properly sought-after and we will do that and that's a job for the police," he added.

Control orders are used on terrorism suspects when there is not enough evidence for a criminal prosecution - they can be tagged, confined to their homes and banned from communicating with others.

It's more than an embarrassment - these are people they describe as being a danger to the public David Davis Shadow home secretary Control orders explained Orders 'are second best'

A major police investigation is ongoing after the men's disappearance, and it is understood ports and airports have been notified.

The British suspect, who is of Pakistani descent, is accused of wanting to go to Iraq to fight. He had been subject to a control order since March.

The second man, an Iraqi, is thought to have been missing for some months.

Shadow home secretary David Davis has described the escapes as "extraordinary".

'Danger to public'

He said the government had been warned about "weaknesses" in the operation of the orders adding: "It's more than an embarrassment. These are people they describe as being a danger to the public. "

Meanwhile Nick Clegg, for the Liberal Democrats, said: "The danger of control orders is that they short-circuit due process and keep suspects in a state of limbo."

But the prime minister hit back on Tuesday, highlighting the history of the control orders, which were brought in to replace detention without charge or trial of terrorism suspects after the Law Lords ruled it illegal.

"We wanted far tougher laws against terrorism, we were prevented by the opposition in Parliament and then by the courts in ensuring that was done," he said.

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"Some of the self-same people who are criticising us on control orders today were leading the charge against the legislation that would have allowed us to detain these people," he said.

Tony McNulty, a Home Office minister, said there may be a need for a stronger version of control orders which would depart from the European Convention on Human Rights.

Andrew Dismore, chairman of the Commons and Lords committee on human rights, said government efforts should be targeted now at "trying to improve its efforts to prosecute those involved".

The family of the British suspect say they are concerned for his safety and are appealing for his return to fight the allegations against him.

Shami Chakrabarti, director of human rights group Liberty, said control orders did not work.

"If someone is truly a dangerous terror suspect, why would you leave them at large?