US security officials were thoroughly checking the identities of foreign flight crews and had questioned a few people with names that appeared to be similar to those on the FBI's "watch lists of suspected terrorists", the report said on Wednesday, citing Bush administration sources. 

Officials declined to identify the air carriers involved, the newspaper reported. Passengers coming into at least one major US international airport on Air France and flights from Mexico will be subject to more security procedures beginning on Wednesday, the report said, citing an aviation industry official and two other sources. 

Passengers scrutinised

The US Department of Homeland Security said it asked
international carriers to tighten security in light of the
elevated alert for "terrorist attacks". 

"At this time, our customs and border-protection inspectors
are increasing scrutiny of all international passengers coming
into the United States," said Department of Homeland Security spokesman Brian Roehrkasse. 

The Washington Post quoted law enforcement officials as
saying they were concerned about security throughout the United Sates, but in particular in Washington, New York, Los Angeles and Las Vegas. 

A US Department of Homeland Security memo to US
airports, issued on Sunday and obtained by the newspaper, said the department continues "to receive uncorroborated reports that extremists may attempt to hijack or bomb commercial aircraft both in the United States and abroad."