Terror suspect Mohammed Ahmed Mohamed cut off his own monitoring tag with a sharp object before fleeing, it has been reported.
According to the BBC, the tag - imposed as part of a terrorism prevention measure - issued a "tamper alert" to its makers, the private security firm G4S.
They rang the suspect and contacted the Home Office after he failed to answer. Police were alerted but he had fled.
The suspect has been on the run since last Friday after evading surveillance by leaving a London mosque wearing a burqa that covered his face and body.
ITV News understands the 27-year-old has attended an Al-Shabaab training camp and fought for them on the front line in Somalia. He has also helped those from the UK travelling to Somalia to train.
Somali-born Mohammed has also been involved with the procuring of weapons and played a role in planning attacks on Somalia and overseas.