Image caption Ibrahim Magag was last seen in north London on Boxing Day

The government has "important questions" to answer over how a terror suspect absconded while under an anti-terror control measure, shadow home secretary Yvette Cooper has said.

Police are continuing to search for Ibrahim Magag, who disappeared from Camden, north London on Boxing Day.

He was previously subject to a control order but they were replaced by TPim control measures last January.

His disappearance had "nothing to do" with the switch, the Home Office said.

Detectives appealed for help on Monday in finding Mr Magag, who failed to meet his overnight residence conditions on the 26th December.

Mr Magag, 28, of Somali origin, was last seen in Camden at 17:20 GMT on Boxing Day.

Return to London

TPims - or Terrorism Prevention and Investigation Measures - restrict the movements of people thought to pose a risk to the public, but who cannot be tried for reasons of national security or who cannot be deported.

Those who are subject to such orders can face restrictions, such as where they stay, who they contact, and where they travel, but they are not forcibly relocated.

The identity of people under TPims are usually kept secret, but an anonymity order imposed on Mr Magag was lifted following a request by the police.

In a statement, Ms Cooper questioned whether allowing Mr Magag to return to London under a TPim contributed to his absconding.

Image caption Yvette Cooper said Theresa May needed to explain why surveillance on Mr Magag failed

"Ibrahim Magag was previously on a control order and relocated to the West Country - a decision upheld by the courts.

"The home secretary took the decision against the advice of security experts to replace control orders with TPims, removing the power to relocate terror suspects and reducing restrictions.

"Theresa May needs to explain rapidly why surveillance failed on Ibrahim Magag since Christmas and whether her decision to return him to London and to weaken legislation has made it easier for him to abscond and harder for the police to find him now," she said.

Labour MP Pat McFadden also accused the coalition of putting the public "at risk" by abolishing control orders.

Speaking to BBC Radio Four's World at One, described TPims as "watered-down control orders" which grant "more freedoms" to terror suspects.

"I think what they have done is complacent and dangerous and I warned the home secretary and the prime minster about this when the legislation was going through."

Control orders introduced under Labour placed terror suspects under close supervision which critics described as similar to house arrest.

Ten people in the UK are currently subject to a TPim notice, according to the Home Office.

'Pretty oppressive'

A spokesperson for the Home Office said Mr Magag's disappearance was "the first time somebody subject to a TPim has absconded".

They added: "In the six years of control orders, there were seven absconds, and in six of those cases the individual was never found in the UK.

"The TPim regime provides effective powers for dealing with those who are engaged in terrorism-related activity but who we cannot yet prosecute or deport.

"By providing extra funding to the security services and Metropolitan Police we are maximising the opportunities to put these individuals on trial in open court."

David Anderson QC, the independent reviewer of terrorism legislation, told the BBC he agreed the replacement measures were "watered down", but nevertheless were "still pretty oppressive".

He added the end of relocation powers had been balanced by increased resources for surveillance, and TPims were limited to two years as opposed to the indefinite length of control orders.

Writing on Twitter earlier, Mr Anderson questioned whether Mr Magag would have been able to abscond as easily from south-west England, where he was held under his control order from 2009 until 2011.

But he added no anti-terror measure "of this kind" is "foolproof". He highlighted that the UK does not imprison British citizens who have "not been charged or convicted of a criminal offence".

Ministers say they do not believe his disappearance is linked to any terrorism planning in the UK, and his TPim was intended to prevent fundraising and overseas travel.