Terror threat still 'very serious'

The chaos gripping Britain's aviation industry has begun to ease after the official terrorist threat level was lowered from its most critical rating.

Four days after police and MI5 smashed an alleged plot to blow up transatlantic passenger jets and stringent security checks were introduced, the threat level was reduced a notch from critical to severe.

That prompted a slight relaxation of the security regime at Britain's airports in a bid to ease the congestion endured by thousands of passengers since last Thursday's anti-terror raids.

However, the new regulations still leave Britain with one of the strictest pre-flight security routines in the world and much tighter constraints on the size of hand luggage.

Home Secretary John Reid and Transport Secretary Douglas Alexander said the measures were necessary because there was still a "very serious" risk of a terror attack, despite the downgraded threat level.

The severe rating meant an attack was still high likely, but no longer imminent, Mr Reid explained.

Detectives investigating the plot, in which the suspects allegedly planned to explode liquid-based explosive devices smuggled in hand luggage while in mid-flight, were continuing to question 23 people.

They were also conducting searches at several locations linked to the investigation, code-named Operation Overt.

Specialist officers were combing woodland at King's Wood in High Wycombe, Buckinghamshire, close to the scene of one of last Thursday's raids.

However, Scotland Yard remained tight-lipped amid unconfirmed claims that police had found a rifle and a handgun and "suspicious" components during the searches.