Officers from the MPS Counter Terrorism Command have detained a man in Maidenhead. The man, 22, has been detained on suspicion of 'commission, preparation or instigation of terrorism'.
He is at present in custody in a central London police station. Officers are at present searching two residential addresses and one business address in Berkshire.
No firearms officers have been deployed during the course of today's pre-planned operation.
A man and a woman have been detained by specialist officers at Heathrow Airport on the suspicion of "the commission, preparation or instigation of acts of terrorism".
It's understood that the couple were arrested after arriving on a flight into the airport.
Police are searching two separate addresses in East London as part of their inquiry.