LONDON — British police arrested a group of suspected Islamic extremists Monday in what officials called one of the most significant counterterrorism operations of the year.
Officers were also carrying out raids on more than a dozen homes and businesses in the central England city of Birmingham as part of the intelligence-led operation.
Although the plot was in its early stages and targets weren’t immediately known, British security officials said the threat appeared significant and involved Islamic extremists. Authorities said it didn’t appear that fall political conferences by Britain’s main parties were the intended target.
Marcus Beale, West Midlands assistant police chief, said the suspects were arrested in or near their homes by unarmed police officers as part of a “large, pre-planned, intelligence-led counterterrorism operation.” Six men were arrested overnight and were being held on suspicion of the “commission, preparation or instigation” of an act of terrorism in Britain.
A woman was arrested Monday morning for failing to disclose information. The suspects’ ages are between 22 and 32. All were described as being British residents, and police would not give any details about nationalities or ethnicity.
Beale said police were searching 14 properties and had removed computer equipment.
Britain’s national terrorist threat level remained at “substantial” Monday. Britain lowered its assessment of a terrorist attack from “severe” to “substantial” in July. The current threat level means risk of an attack is a “strong possibility.”
Last year, British authorities arrested 12 suspects in a large- scale terrorist plot aimed at attacking British landmarks and public spaces.
At least five of the men were of Bangladeshi origin. Some of their cases are still pending.
Europe has been the target of numerous terrorist plots by Islamist militants.
The deadliest was the 2004 Madrid train bombings, when shrapnel-filled bombs exploded, killing 191 people and wounding about 1,800.
In 2005, suicide bombers killed 52 rush-hour commuters in London aboard three subway trains and a bus.
