WASHINGTON, Jan 5: The United States on Monday began taking pictures and fingerprints of most arriving foreigners as part of a heightened anti-terrorist campaign but received key backing in its demand for armed sky marshalls on some flights.

Visitors arriving at US airports seemed resigned to the new measures but they have been opposed by some countries, such as Brazil, which has ordered that US visitors also give fingerprints and have their pictures taken.

But Homeland Security Secretary Tom Ridge insisted the precautions were essential. The US wants to ensure that "our borders remain open to visitors but closed to terrorists," he said at Atlanta airport, one of 115 across the country where the so-called "biometric" defences were introduced. Fourteen ports are also involved.

An estimated 23 million people from countries where visas are required for US visits will this year have to give a digital fingerprint and have a photograph taken under the United States Visitor and Immigrant Status Indicator Technology, or US-VISIT.

Only 28 countries are exempt, mainly European countries, Japan and Australia. "One of the primary responsibilities of any government is to make sure that their borders are secure, and we're doing that with this programme. I think it's very inobtrusive. It takes about 15 seconds and no one seemed to mind," Ridge said.

By next year every entry point into the United States will use the technology. All US visas and passports will eventually include photos and fingerprints.

The US raised its nationwide terrorist attack alert on Dec 21 with Ridge warning that Al Qaeda was planning an even bigger attack than the Sept 11 strikes.

Since Dec 24, seven flights headed for the US - three from France, two from Britain and two from Mexico - have been cancelled due to security fears. A London to Washington British Airways flight which was cancelled twice last week was again delayed Monday, the airline said.

Singapore, meanwhile, expressed strong backing for the US demand made last month for armed sky marshals on sensitive flights into the US and British Prime Minister Tony Blair said the threat of attacks was real across the world.

Singapore's Deputy Prime Minister Tony Tan said air marshals would be deployed on more flights of Singapore Airlines, one of Asia's leading carriers, and that the city republic would work to protect planes from surface to air missiles.

"The threat is real, the threat is urgent, the threat is serious," the Straits Times newspaper quoted Mr Tan, who is also Coordinating Minister for Security and Defence, as saying on Sunday.

He said the presence of armed air marshalls on Singapore Airlines flights would become a regular feature. "It will come to a stage when an airline without air marshals will not be allowed to land at certain airports," Mr Tan predicted.

Mr Tan also raised the spectre of terrorists using surface-to-air missiles, saying Singapore Airlines was trying to ensure its planes were protected from such attacks.-AFP