The 19-year-old arrested at his High Wycombe home on Thursday night on suspicion of being involved in terrorist activity will remain in police custody.

Metropolitan Police today confirmed that warrants for further detention of the four men arrested in Thames Valley and West London have been granted.

This means that the Wycombe teenager, named locally as Yousaf Syed, will remain in custody pending further enquiries.

About 40 officers, some of whom were armed, swooped on the property at about 8.45pm on Thursday.

Metropolitan Police confirmed yesterday that there are three other addresses in High Wycombe that are being searched.

A 22-year-old-man was also arrested at an address in Hounslow at 8.45pm on Thursday, while a 27-year-old man was arrested in a car in Southall slightly earlier at 8.31pm.

Firearms officers assisted with both arrests, although no shots were fired during the course of the operation.

Another man, 25, was arrested at an address in Uxbridge at 2.55am yesterday morning.

All for men have been arrested on suspicion of being concerned in the Commission, Preparation or Instigation of acts of 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.

Police confirmed that these arrests and searches are part of an ongoing investigation into Islamist related terrorism.

Police taped was removed from the perimeter of the property and the family are believed to have been moved to a "safehouse".