The fingerprints will then be matched against a database of known criminals and terrorists.

The visitors will also be required to check in periodically with authorities, similar to programmes adopted by several European countries.

'Racial profiling'

The measures have been criticised by civil rights campaigners, who say some visitors will be treated unfairly.

"This is a fancy way of racial profiling," Carl Baron, immigration attorney and researcher at the University of Texas, told the Associated Press news agency.

"Just on the basis of where a person is from the government is going to subject them to these measures.

"You're going to see fewer Middle Easterners willing to come to the United States and I wonder whether that isn't the real agenda."

But the INS has dismissed the allegations as unfounded.

"The real agenda is to improve security in the United States and improve the knowledge of who is coming and what their business is here," Bill Strassberger, INS spokesman said.

"The terrorists were able to exploit what they perceived as weaknesses. We can make sure that won't happen again."

Experts say that under anti-terrorist legislation passed late last year, the US Congress wants to track virtually all of the 35 million foreign visitors who come to the US annually by 2005.