SAN FRANCISCO, Jan 22: Security agents in the United States have a master list of five million people worldwide thought to be potential terrorists or criminals, media reports here said.

"The US lookout index contains some five million names of known terrorists and other persons representing a potential problem," Brian Davis, a senior Canadian immigration official, was quoted as saying.

Names on the list are compared against those applying for visas or on flights travelling to the US. Anyone whose name is on the list is questioned or banned from entering the US - as passengers were on two British Airways flights to Los Angeles two weeks ago.

Mr Davis said Canadian visa officials abroad do not keep an extensive list like the US because terrorists can use bogus documents and change their identities.