WASHINGTON, USA (AP) The United States government is refining its terror-screening policy to focus on specific terror threats and not travellers' nationalities.

The new policy replaces a security requirement put in place after the attempted bombing of a jetliner en route to Detroit on Christmas Day that singled out people from 14 countries that have been home to terrorists. It also expands the pool of foreign travellers targeted for extra screening beyond those whose names are on a US terror watch list.

The changes, announced yesterday by the Homeland Security Department, come after a three-month review of counterterrorism policies ordered by President Barack Obama in the wake of the near miss attack.

Under the refined policy, a person travelling to the US would be stopped if he or she fits a specific description of a potential terrorist provided by US intelligence officials -- even if the suspect's name is unknown.

Currently, passengers' names are compared to names on US terror watch lists. If air carriers have a potential match to a watch list, the passenger is either banned from flying to the US or subjected to extra screening such as a full-body pat-down before boarding the airplane.

For example, if the US has intelligence about a Nigerian man between the ages of 22 and 32 whom officials believe is a threat or a known terrorist, under the new policy all Nigerian men within that age range would receive extra screening before they are allowed to fly to the US.

If intelligence later shows that the suspect is not a terrorist, the extra screening for others matching the description would be lifted.