WASHINGTON (AFP) - US authorities can place Americans and foreigners on a terrorist watchlist indefinitely on the basis of vague rules without concrete evidence, according to a government document leaked on Wednesday.
Once blacklisted, individuals have no way of finding out why they are deemed suspicious and even dead people's names remain on the list, under the secret guidelines set out last year by the National Counter-Terrorism Centre (NCTC), which were published for the first time by The Intercept news website.
The new rules introduced by President Barack Obama's administration represent an expansion of the US government's power in overseeing the terrorist database, laying out broad criteria for adding names to the blacklists, The Intercept reported.
Individuals added to the watchlists can be banned from flying - under the "no-fly" list - or subjected to additional searches and security screening at airports and border crossings.
US authorities took a tougher approach to the watchlists after Al-Qaeda militant Umar Farouk Abdulmutallab tried to blow up an airliner bound for Detroit on Christmas Day 2009.
A civil court case recently revealed that the watchlist has dramatically grown in recent years, with the government adding 1.5 million names to the blacklist since 2009.
Human rights groups slammed the rules for the watchlist, saying the government had created an unaccountable, overly broad system.
"Instead of a watchlist limited to actual, known terrorists, the government has built a vast system based on the unproven and flawed premise that it can predict if a person will commit a terrorist act in the future," said Hina Shamsi, director of the American Civil Liberties Union's national security project.
Shamsi accused the government of offering virtually no recourse to someone trying to clear their name.
She said the "government's watchlist 'redress' system won't confirm or deny watchlisting, and doesn't provide reasons or a hearing to clear a person's name of terrorism stigma".
The NCTC, which would not confirm or deny the document's authenticity, defended the watchlist as a useful tool in preventing terror attacks and that it was frequently reviewed and vetted.
"Before an American may be included on a watchlist, additional layers of scrutiny are applied to ensure that the listing is appropriate," said a spokesman for the centre, who gave a statement on condition of anonymity.
Suspects who reportedly die are kept on the watchlist "to prevent the fraudulent reuse of their travel documents - a demonstrated terrorist tactic", she told AFP.