By Ellen Wulfhorst

NEW YORK (Reuters) - More stringent screening launched on Monday for airline passengers from 14 nations, part of a crackdown after the botched Christmas Day bombing of a Detroit-bound flight, are ineffective and unconstitutional, civil liberty groups charged.

The tighter security measures, which range from passengers being patted down to advanced explosives detection and full-body scans, constitute racial profiling when there is no realistic way to predict the national origin of a potential attacker, the American Civil Liberties Union said.

The measures announced by the U.S. Transportation Security Administration affect passengers arriving from Cuba, Iran, Sudan and Syria -- nations listed as "state sponsors of terrorism" -- as well as Afghanistan, Algeria, Iraq, Lebanon, Libya, Nigeria, Pakistan, Saudi Arabia, Somalia and Yemen.

"Every individual flying into the U.S. from anywhere in the world traveling from or through nations that are state sponsors of terrorism or other countries of interest will be required to go through enhanced screening," the TSA said.

Michael German, national security policy counsel with the ACLU Washington legislative office, said that singling out travelers from a few specified countries for enhanced screening "is essentially a pretext for racial profiling, which is ineffective, unconstitutional and violates American values."

"We shouldn't complacently surrender our rights for a false sense of security," he said in a statement.

SUBDUED BY PASSENGERS

The move comes in the wake of the failed bombing of a Detroit-bound Northwest Airlines flight on December 25. A 23-year-old Nigerian, Umar Farouk Abdulmutallab, was subdued by passengers and arrested after allegedly trying to detonate a bomb sewn into his underwear on the flight from Amsterdam.

U.S. authorities say he was a member of al Qaeda and was trained and equipped by the Islamic militant network in Yemen.

With 13 of the 14 nations cited by the TSA being majority Muslim, the procedures amount to ethnic profiling, said the Washington-based Council on American-Islamic Relations (CAIR), a Muslim civil rights and advocacy organization.

"Under these new guidelines, almost every American Muslim who travels to see family or friends or goes on pilgrimage to Mecca will automatically be singled out for special security checks -- that's profiling," said CAIR National Executive Director Nihad Awad in a statement.

"While singling out travelers based on religion and national origin may make some people feel safer, it only serves to alienate and stigmatize Muslims and does nothing to improve airline security," Awad said.