A terror suspect who disguised himself as a woman to escape surveillance is believed to have been cleared of tampering with his electronic monitoring tag on the day he went missing.
Mohammed Ahmed Mohamed, who was last seen fleeing a mosque while wearing a burka, is understood to have received training and fought overseas for al-Shabaab, the Somalia-based cell of the militant Islamist group al Qaida.
On the day of his disappearance, he was cleared at the Old Bailey of tampering with his tag, it is understood.
David Anderson QC, the independent reviewer of terrorism legislation, had revealed that criminal charges had been dropped on Friday against a number of Terrorism Prevention and Investigation Measures (Tpim) subjects for allegedly tampering with security tags, but did not specify whether Mohamed was one of those involved.
The Crown Prosecution Service would not comment on named individuals but said in a statement that the cases of three Tpim subjects had recently been discontinued. There were outstanding alleged offences against one of the three, known as CC, who is due to stand trial in April, they added.
The spokeswoman said: " When we authorised charges in these cases, we did so after a review of the available evidence, including that of an expert who believed that the tags had been deliberately damaged by the individuals required to wear them under the Tpim regime.
"Following further inquiries by the police and a review of new material we are unable to prove to the criminal standard that the subject of the Tpim deliberately damaged the tag. As there was no longer a realistic prospect of conviction, we offered no evidence against the two defendants and stopped the case.
"As is our usual practice at the conclusion of our cases we will be speaking with the police and other partners to discuss any issues raised by these cases."
Home Secretary Theresa May has insisted that 27-year-old Mohamed does not pose "a direct threat" to members of the public, despite mounting concerns over his disappearance. He is the second person to breach a Tpim notice since they were introduced to replace control orders in early 2012.
Mrs May told MPs: "The police and security service have confirmed that they do not believe that this man poses a direct threat to the public in the UK. The reason he was put on a Tpim in the first place was to prevent his travel to support terrorism overseas."
Mohamed entered a west London mosque on Friday in Western-style clothes but CCTV images showed him leaving with his face and body fully covered by a burka - the traditional Islamic garment for women.
In December, Tpim subject Ibrahim Magag ripped off his electronic tag and vanished in a black cab.
Both men were members of a UK-based network for terrorism-related activity in Somalia, court documents have revealed.
"The police have urged anyone who sees Mohamed or knows of his whereabouts not to approach him but to call 999 or to contact the anti-terrorist hotline," Mrs May said.
"Their focus is to locate and arrest Mr Mohamed. They are doing everything in their power to apprehend him as quickly as possible and the Government will provide them with all the support they need."
Mrs May addressed the Commons as she came under increased pressure to explain how Mohamed was able to abscond.
Shadow home secretary Yvette Cooper described the situation as "extremely serious".
"Clearly police and security agencies will be doing everything possible to locate this terror suspect and ensure public safety," she said.
"The Home Secretary also needs to provide information about the decisions made over Mohammed Ahmed Mohamed's Tpim, how he was able to abscond and what the risks to the public are."
Ms Cooper added that Ms May needs to "provide rapid information about the extent and adequacy of the restrictions" on Mohamed.
Somalia-born Mohamed, who is 5ft 8in and of medium build, is "not considered at this time to represent a direct threat to the public", Scotland Yard said.
He was named after a court-imposed anonymity order was lifted to allow police to make a public appeal.
It is understood he took part in terrorist training in 2008 and is believed to have helped various individuals travel from the UK to Somalia to allow them to engage in terrorism-related activity.
Mohamed is also suspected of helping to plan attacks in Somalia and overseas, including an attack intended for the Juba Hotel in Mogadishu in August 2010.
It has been reported that Mohamed has links to British terrorist suspect Samantha Lewthwaite, who was married to the July 7 bomber Jermaine Lindsay. She is known to be in East Africa and is wanted by Kenyan police over alleged links to a terrorist cell that planned to bomb the country's coastal resorts.
Mohamed arrived at the An-Noor Masjid and Community Centre in Church Road, Acton, at 10am on Friday and was last seen there at 3.15pm that day. T he mosque said it did not intend to comment.
Along with 28-year-old Magag and others, Mohamed is thought to be a member of a UK-based network which had access to money, false passports and documentation, as well as equipment
Mohamed is understood to have procured funds and weapons for terrorism uses for the network.
Magag was made the subject of a stringent control order in 2009 but the restrictions expired when control orders were replaced by Tpims last year.
A Scotland Yard spokesman said: "The Counter Terrorism Command immediately launched inquiries to trace Mr Mohamed and these continue.
"Ports and borders were notified with his photograph and details circulated nationally. Public safety remains our priority."
Tpims, which include restrictions on overnight residence, travel and finance, are imposed by the Home Secretary, who is given access to secret evidence that cannot be placed before juries. They do not allow for the relocation of suspects, as control orders did.
Unlike control orders, Tpims have a maximum time limit of two years. Control orders could be extended year on year without limit, while Tpims can be extended after a year for another 12 months before they expire.
There were nine Tpims in force as of August 31, including eight against British suspects.
The terrorism watchdog warned earlier this year that Tpims could allow those deemed potentially dangerous to be left "free and unconstrained" in the absence of prosecution or new evidence of terrorism-related activity.
Mr Anderson said in his first report on Tpims in March that the two-year limit was the "boldest" change from control orders made by the Government, adding that it was "tempting, in the most serious cases, to wish for longer".
Commenting after Mohamed's disappearance, Mr Anderson said prosecutions for Tpim breaches are "difficult".
He added: "Criminal charges against a number of Tpim subjects for allegedly breaching the terms of their Tpims by tampering with their GPS tags were dropped on Friday after no evidence was offered by the Crown."
Asked whether Tpims work during a visit to a Hindu temple in Neasden, north-west London, Prime Minister David Cameron said: "They do work but when there's a problem as there is with this case we need to act very, very quickly and get on top of it and we will."
Security minister James Brokenshire defended the measures, describing them as providing a "robust mechanism" to manage suspects and reassure the public.
He said: "National security is the Government's top priority and the police are doing everything in their power to apprehend this man as quickly as possible. The police and security services do not believe that this man poses a direct threat to the public in the UK."