A woman from Croydon is one of three arrested in a police investigation into alleged blackmail linked to animal rights extremism.
Officers from the Metropolitan Police Counter Terrorism Command (CTC) arrested the 50-year-old woman on suspicion of conspiracy to blackmail, this morning.
She was taken to a south London police station where she remains in custody.
A 25-year-old woman and a 25-year-old man were also arrested at a residential address in Amsterdam, after officers from the Dutch National Crime Squad executed a European Arrest Warrant in connection to the investigation.
The pair also remain in custody and officers are searching the address where the arrests were made.
A business address connected to the operation is also being searched.
The three arrests mark a significant development in a long-running, proactive investigation into alleged criminal activity across Europe.
The operation has been led by the Met Police CTC, in liaison with the National Domestic Extremism Unit (UDEU) and the Dutch National Crime Squad.