UK terror threat level downgraded
The terror threat to the UK has been
downgraded from "critical" to "severe".
The change in the threat level means the ban on taking hand luggage on to flights from the UK has been lifted, although some restrictions remain.
Meanwhile, a British Airways flight from Heathrow to New York has been turned back because a mobile phone - banned at the time - was on board.
The change in the terror threat level was made by the Joint Terrorism Analysis Centre based on latest intelligence.
The threat level was heightened last week amid fears of a possible plot to blow up transatlantic airliners. This prompted a number of arrests on Thursday.
Officers are continuing to question 23 people in the inquiry.
Mr Reid said although police believe the main suspects in the alleged plot had been arrested, there was still the threat of a terror attack.
Speaking at a press conference on Monday, the home secretary warned that "the change in the threat level does not mean that the threat has gone away".
He said: "The public needs to know that there may be other people out there who may be planning to attack against the United Kingdom.
"That is why there are a number of other security service operations underway. There is still a very serious threat of an attack."
Meanwhile, the US Department of Homeland Security has downgraded the threat level for flights from the UK from "code red" to "code orange".
The UK has been at the highest level of terror threat since police made arrests last Thursday in connection with the alleged plot to use liquid explosives on planes from the UK to the US.
But airport operator BAA has urged passengers using Heathrow, Gatwick and Stansted not to bring hand baggage as it gradually phases in the latest changes.
It said the new rules on hand luggage will not come into force at all of its seven airports until Tuesday morning.
The company says it will need to brief its thousands of security staff, who will not be aware of the change because it was announced overnight.
The Department for Transport said passengers would now be allowed to carry one item of hand luggage on to flights, although there would still be some restrictions in place.
The department hoped the change would help ease congestion at airports.
Long-term changes to airport security checks outlined by Transport Secretary Douglas Alexander include the following:
A medium-sized item of hand luggage will be permitted. This bag will be around half the size of luggage previously admitted.
Searches of passengers and their clothing will
be conducted more frequently and are to be carried out by hand or using
No one admitted owning the phone so flight BA179 with 217 passengers on board returned to Heathrow as a precautionary measure, prompting BA to apologise for inconvenience, although it said safety was its "number one priority".
Before the restrictions were changed, travellers had been told to expect more cancellations and delays at UK airports.
Deputy Prime Minister John Prescott visited Stansted airport to see how the security measures were being put into practice.
Meanwhile, detectives investigating the alleged plot are conducting a major search for evidence at King's Wood near High Wycombe in Buckinghamshire, near the scene of one of the raids.
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