British police detained one more person this evening in connection with last week's alleged plot to blow up transatlantic airliners, as France's interior minister said the threat of terrorism remained "high and permanent".
The arrest took the number of people held in Britain to 24 after police said last Thursday they had foiled a plan to carry out multiple suicide bombings on aircraft bound for the United States using liquid explosives disguised as drinks.
French Interior Minister Nicolas Sarkozy told France 2 television that information France had received from Britain showed the authorities had faced a "serious" and "imminent" threat.
British police - who are conducting searches in at least three parts of the country - said they had arrested another suspect in the Thames Valley area in southeastern Britain, where officers raided several houses last week.
The 23 people already being held in Britain are all British-born Muslims, mainly of Pakistani descent. No details were immediately available on the latest arrest.
Police must get a judge's approval tomorrow to continue to hold those detained last week. Suspects can be held for up to 28 days without charge under new powers introduced last month.
The Pakistan government said on Friday it had arrested seven people, including two British Muslims of Pakistani descent. One of the Britons, Rashid Rauf, has links to al Qaeda, it said.
A Pakistani intelligence official also said this week authorities were probing two Islamic charities, al Rasheed Trust and al Asar Trust, over a possible financing role.
Authorities were investigating whether money donated in Britain to provide relief to victims of last year's earthquake in Pakistani-held Kashmir had been diverted to fund the alleged plot to blow up the planes, he said.
British police on Tuesday combed woodland around the town of High Wycombe, in the Thames Valley, for evidence of the alleged plot.
One of the houses raided in High Wycombe, according to British media, may have been used by the alleged plotters to mix the chemicals to blow up as many as 10 US-bound aircraft.
The suspected plot came 13 months after British Muslim suicide bombers killed 52 people on London's transport system.
It caused chaos at Britain's major airports as all airline cabin baggage was banned. Britain eased that ban on Monday as it scaled down the threat level to "severe" from "critical".
But passengers continued to suffer major delays today and airlines were still forced to cancel some of their flights.
British Airways, which has been forced to cancel 1,100 flights since security checks were stepped up, said it might seek compensation from airport operator BAA.
Mountains of baggage piled up at Heathrow, the world's busiest international airport, as BA said it was still trying to clear a backlog of 5,000 bags and deliver them to their owners.
Agencies