Armed police have arrested four suspected Islamic terrorists at addresses in west London and Thames Valley.
Three men, aged 19, 22, 25, were arrested after warrants were executed at addresses last night and have all been taken to police stations in central London where they remain in custody.
Two of the entries to premises were assisted by firearms officers. No shots were fired.
A number of residential addresses and vehicles are being searched by specialist officers in west London and Thames Valley as part of the investigation.
These arrests and searches are part of an ongoing investigation into Islamist related terrorism.
Officers from the Metropolitan Police Service's Counter Terrorism Command (SO15) are working closely with their colleagues in the SE Counter Terrorism Unit and MI5.
The searches are ongoing and enquiries continue.
A number of suspected terrorists have been arrested recently for preparing to join Isis in Syria.
However, a Met Police spokesman refused to confirm whether the four suspects arrested overnight were planning to carry out the alleged terrorism acts abroad or on UK soil.