London: A female Islamic State (IS) recruiter dubbed "Mrs Terror" is reported to have returned to Britain, a media report said on Friday.
Special Branch officers were on full alert after Sally Jones was reportedly spotted in Birmingham with two suspected jihadis, Mirror online reported.
Police were informed that Jones - thought to have arrived in Syria in 2013 to fight for IS - is to be treated as "hostile".
Security has been tightened in airports, shopping centres and event locations.
Earlier this week, it was revealed that she told undercover investigators she had recruited a female terrorist who is in Glasgow and is ready to launch a devastating attack.
During online conversations, 45-year-old Jones and her husband Junaid Hussain, 21, urged the investigators - posing as jihadis - to carry out attacks in Britain and sent them bomb-making guidebooks.
Hussain, from Birmingham, runs the IS recruitment arm in the terror group`s stronghold of Raqqa in Syria.