Four men arrested in Luton on suspicion of terror offences
Four men from Luton have been arrested on suspicion of terrorism offences, Scotland Yard has said.
The men - who are all in their 30s - were arrested on suspicion of being involved in the commission, preparation and instigation of acts of terrorism.
They have been taken into custody at a London police station and seven addresses and several vehicles are being searched in Luton, police said.
The arrests are not connected to last month's attacks in Paris, they added.
The men are also not believed to have been preparing to travel to Syria.
BBC home affairs correspondent Danny Shaw said the arrests were "quite significant" and followed a "long-standing covert police operation" in Luton.
He said no firearms officers were involved, which suggested there was no intelligence of any immediate threat.
"However, there has been heightened concern in the UK that extremist groups are encouraging and radicalising individuals; recruiting people to get involved in Islamist terrorism; and planning attacks," our correspondent added.
The arrests were carried out in a joint operation by the Metropolitan Police's Counter Terrorism Command and the Eastern Counter Terrorism and Intelligence Unit.