GENEVA - Washington's new anti-terrorism law could end up violating international treaties protecting detainees, with some provisions denying suspects the right to a fair trial, a U.N. rights expert said Friday.

Martin Scheinin, the U.N. expert on protecting human rights in the fight against terrorism, said the Military Commissions Act signed into law earlier this month by President Bush contains provisions "incompatible" with U.S. obligations to adhere to treaties on human rights and humanitarian law.

"One of the most serious aspects of this legislation is the power of the president to declare anyone, including U.S. citizens, without charge as an unlawful enemy combatant, a term unknown in international humanitarian law," said Scheinin, a legal expert from Finland.

As a result, he said, those detainees are subject to the jurisdiction of a military commission rather than a civilian court of law.

He also deplored the denial of the habeas corpus rights of foreigners, including legal, permanent U.S. residents, to challenge the legality of their detention "in manifest contradiction with" the International Covenant on Civil and Political Rights, a treaty the U.S. ratified in 1992.

Another concern, Scheinin said, is the denial of detainees' rights to see evidence that could exonerate them if the evidence is deemed classified. That, he said, "severely impedes the right to a fair trial."

Brooks Robinson, a spokeswoman for the U.S. mission to international organizations in Geneva, said the law was written to specifically address those concerns. Robinson said the law was drafted "in consultation with and in response to concerns by our allies and partners."