LONDON, 11 August 2006 — Britain awoke to a country under “critical” security level yesterday morning as chaos reigned at airports following a major overnight counterterrorism operation involving 21 arrests at three locations around the UK and the cancellation of outbound and all but long-haul inbound flights from the UK’s airports.

But British airports operator BAA said it has been given approval by air traffic control authorities later yesterday to resume short-haul flights into and out of London Heathrow airport.

“There is no restriction now on short-haul flights, the restriction that was in place has been lifted” by Britain’s National Air Traffic Services, a BAA spokeswoman said. In total, 302 arrival flights and 309 departures were canceled at Heathrow as of 4:00 p.m. (1500 GMT), according to BAA. The spokeswoman added that there were no restrictions on long-haul flights, although passengers should be prepared for long delays.

Douglas Alexander, Transport Secretary, said that the measures that had been put in place should make people feel safe and allow flights to enter and leave the UK. “The measures were to secure flights from Britain and we were determined to send a signal that notwithstanding the challenges we do face, that we will continue to operate British airports.”

On the ground, security analyst Robert Partidge interviewed from Heathrow said that the situation at the airport was one of “management confusion, not chaos.”

He was critical of the reaction of the security services to handling the situation within the airport. He said that because the perimeter security did not kick in early enough and this allowed passengers to get to the check in desks. These became choke points and burdened the staff there who were not trained to handle such situations.

The UK Department for Transport set out the details of the security measures at UK airports. Passengers are not allowed to take any hand luggage on to any flights in the UK, the department said. Only the barest essentials — including passports and wallets — will be permitted on board and then only in transparent plastic bags.

Chaos reigned at British airports crammed with holidaymakers yesterday. But while departure halls were jammed with people, hand luggage and liquids banned from flights and passengers with babies made to publicly taste their food, the mood was one of calm resignation.

“It’s just part of travel today. It’s just something you have to do and there’s always a risk, and if they’re increasing security this much, we’re probably safer than usual,” said Dale Rosser, 57, queuing at Heathrow to fly back to Michigan. Hotels around Heathrow, the world’s busiest international airport, were booked solid as short-haul flights were canceled briefly. At Terminal One there was a queue more than 100 meters (yards) long of people trying to find accommodation further afield.

“Nobody seemed to know what was going on. These was no communication in the airport. But it is your life you are looking at. They are doing the best they can,” said Sebastian Hover, 33, trying to get to Warsaw from Bristol.

Bars and coffee shops did booming business, with Terminal One bar manager Simon Bell saying more was expected today as people returned to try to resume their journeys.

Matters were not helped by confusing instructions, with some people forced to throw away books they had bought. “I have got my computer and I just heard five minutes ago I won’t be able to take it on. Where should I put them?” asked transit passenger Timo Haikonen, 57, on his way to holiday in Chicago from Helsinki.

As passengers neared the front of a security check queue at Terminal Three, one of the main departure points for flights to the United States, an official told them: “No drink, no books, no chewing gum and no food,” without offering any explanation. “I am just going to be really bored on the plane because I have got nothing to do,” complained 10-year-old Stephanie Sheldon, queuing moodily with her parents on the way from Birmingham to holiday in Miami.

While Heathrow was the worst hit, there were similar scenes at major airports across the country. Manchester airport, another major departure point for the United States, experienced severe delays. At Stansted airport, north of London, there were considerable delays to flights and 40 were canceled. But phlegmatic passengers said the inconvenience of a delay was a small price to pay for their safety.

Many airlines said they were canceling all flights to Britain and to the epicenter of the threat, London Heathrow, one of the world’s busiest airports, and warned the problems could last for several days.

The inter-connected nature of international air travel meant the disruption caused by chaos at Heathrow in the wake of the new measures was rippling out across the world.

In contrast to their European counterparts, and despite a request by the British Airports Authority, US airlines said they were not planning to cancel flights to Heathrow, but warned of severe delays.

Short-haul international flights to and from British provincial airports were less affected.

No-frills operator easyJet canceled all its remaining flights due to depart yesterday from three airports bordering London.

Other European airlines were forced to ground many of their flights. Lufthansa of Germany said it was pulling all flights to Britain until 1500 GMT. It said 22 flights and 3,041 passengers would be affected, but that it expected flights later in the day to go ahead as planned.

Flights between Spain and Britain, normally full of holidaymakers at this time of the year, were severely disrupted. Spanish national carrier Iberia had canceled nine flights by mid-afternoon and airport authority AENA said it had been told that no flights could land at Heathrow before 1400 GMT.

Italy’s Alitalia suspended all its flights to Britain and aviation authorities in the Netherlands said they were canceling all flights to Heathrow until at least 1800 GMT. An estimated 1,500 passengers on KLM flights from Amsterdam’s Schiphol airport had been affected by 1300 GMT.

French airline Air France said it had canceled all its 10 flights to Heathrow until 2000 GMT, among a total of some 50 in all scratched from France to the London airport. They included 25 from Paris’s main airport Charles de Gaulle, three from Orly and eight from the Mediterranean city of Nice, leaving hundreds of passengers stranded, airport officials said.

Turkey, Greece, Denmark and Sweden also suspended flights to London. The Russian Transport Ministry said it was leaving the decision to individual airlines, but Aeroflot said its morning flight to Heathrow had landed as normal.

US airlines, believed to be the targets of the alleged bomb plot, said they were not canceling flights, but the US Department of Homeland Security issued its highest-level threat warning for all US-bound planes from Britain. “It’s a fluid situation. But we have no cancellations of UK-bound flights,” said Brandon Borrman, a spokesman for United Airlines.

In Asia, Japanese airlines said they were waiting for further information and that it was highly possible they would have to cancel flights to Britain. Thai Airways said one of its flights took off for Heathrow around 0500 GMT. Other flights to London were to leave Bangkok around 1700 GMT and so far none had been delayed or canceled, a spokesman said. Airport officials and travel agents in China reported no cancellations or delays of flights although Hong Kong’s flag carrier Cathay Pacific warned of delays going to London.

African airlines were also affected. A spokesman for Kenya Airways said it would comply with requests from the British authorities to introduce new restrictions on hand luggage.

— With input from agencies