Exclusive video obtained by ITV Cymru Wales appears to show a man being detained by officers on a residential street in Newport.
The Metropolitan Police have confirmed a 25-year-old man was arrested shortly after 7pm on Tuesday in connection with the Parsons Green terror attack.
The arrest was carried out by officers from the Met's Counter Terrorism Command, supported by colleagues from Gwent Police and the Welsh Extremism and Counter Terorrism Unit.
Officers also confirmed a search took place at an address.
A residential street in the Maindee area of the city was cordoned off this evening.
Two men aged 18 and 21 remain in custody in connection with the south west London bomb attack.