UK diplomats say they are working with their US counterparts to try to save thousands of British visitors having to apply for visas to enter the US.
British travellers are to be fingerprinted on arrival in the US
Currently British travellers can visit the US for up to three months without a visa under the "visa waiver" scheme.
But new passports issued after 26 October must hold "biometric" data such as digital images or fingerprints - or a visa will be needed.
The UK authorities will not be able to issue such passports before mid-2005.
British travellers holding a "machine-readable" passport - issued in Britain since November 1991 - can still travel to the US without a visa for the 10-year lifetime of their document.
They will then have their fingerprints and photographs taken on arrival in the US.
But those who get a new passport after October 26, but before biometric ones are available, will have to purchase a visa at a cost of £67.
More than four million Britons a year travel to the US, and hundreds of thousands of them would be affected by the arrangements as they currently stand.
British officials are believed to be lobbying Washington hard to extend the
deadline or make alternative arrangements.
Correspondents say most other visa waiver countries - mainly in western Europe, but also including Japan and Australia - will also be unable to issue "biometric" passports before the US deadline.
A British Embassy spokesman said: "We are in close contact with the
Department of Homeland Security on the issue of biometrics, and have been from
the start, and we continue to work to find a solution."
Homeland security secretary Tom Ridge said the US aimed to be
"open to visitors but closed to terrorists".
About 15.1 million tourists entered the US under the visa waiver
programme last year, accounting for two-thirds of spending by foreign visitors.
Holidaymakers heading for winter sunshine breaks in Florida and ski resorts for the early season are likely to be among the first of many queuing for visas at the American Embassy in Grosvenor Square, London.
On Monday, stringent new security regulations were introduced at
the US's 115 international airports and 14 major seaports,
The system allows officials to instantly check an immigrant or visitor's
Since 11 September 2001, flying anywhere has changed. Two of the hijackers on that day had entered the US on student visas, but neither ever turned up for college.
The Department of Homeland Security believes the extra immigration checks would have picked up on that discrepancy.
For the American Government there can never be too many checks. Air travel may now be more complex but the US administration is adamant it will not deter visitors from heading to the US.
Instead, they believe the very public extra security is a reassurance - an obvious sign that America is looking hard for those who threaten its citizens.