Officers arrested a 20-year-old man in west London this morning on suspicion of preparing acts of terrorism contrary to section 5 of the Terrorism Act 2006.
He was arrested under the Police and Criminal Evidence Act (PACE) in west London at 6.50am.
He is in custody, the Met Police said, at a central London police station and officers are searching a residential address in west London.
In a separate statement, the Met said its detectives from the Met Counter Terrorism Command arrested a 23-year-old woman in north London this morning.
She was arrested on suspicion of preparing for acts of terrorism as part of a joint investigation with the Belgian Federal Police into facilitating travel to Syria.
The woman has been detained under PACE.
Officers have searched two residential addresses in east London and continue to search another address in north London.
The police said enquiries continue.
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