WASHINGTON (AP) _ Secretary of State Colin Powell on Friday designated Chechen rebel leader Shamil Basayev a threat to the security of the United States and to U.S. citizens.

Powell, in a notice in the Federal Register, said Basayev, 38, ``has committed, or poses a significant risk of committing, acts of terrorism'' against U.S. interests.

The State Department said Basayev has links to the al-Qaida terror network. Together with Britain and Russia, the United States asked the United Nations to impose travel sanctions on him and to block shipment of arms and financial contributions to the rebels by all U.N. members.

``We believe that Basayev, as leader of his group and individually, took part in planning and perpetrating terrorist attacks,'' State Department deputy spokesman Philip T. Reeker said.

He claimed responsibility for seizing the Dubrovka Theater in Moscow last October, an act of terrorism that resulted in the death of 129 hostages, including a U.S. citizen, Reeker said.

And last December, Chechen suicide bombers destroyed the Chechen administration complex in Grozny, killing 78 people and wounding 150, Reeker said in a statement.

It cited other terror attacks and said last November the rebel leader warned governments that were members of international organizations with offices in Russia they would be targets.

The Treasury Department's Office of Foreign Assets Control acted to freeze any assets Basayev might have in the United States and any attempt to transfer the funds.

The designation accelerates a growing understanding between the Bush administration and the Russian government that rebel leaders in the breakaway republic of Chechnya use terror as a tactic.

The Bush administration began to edge toward the Russian view after the United States felt the lash of terror in the Sept. 11 attacks on the World Trade Center in New York and the Pentagon in Arlington, Va.

Chechen rebels, using a shoulder-fired missile, shot down a Russian military helicopter Thursday, killing three members of the crew.

At least seven other Russian servicemen died in attacks and rebel land mine explosions over the past day, an official in the Moscow-backed Chechnya administration said.

Basayev has taken responsibility for a series of suicide attacks in May that killed nearly 100 people as well as the hostage-taking at the Moscow theater.

U.S. officials have been trying to trace funding to Osama bin Laden and his terror network.

In Moscow, Sergei Yastrzhembsky, the Kremlin's chief spokesman on Chechnya, said Powell's action ``is a step in absolutely the right direction. It is another confirmation that within the anti-terrorist coalition there is a deepening understanding that what is happening in Chechnya is inseparable from the battle against terrorist threats in the world.''

Treasury on Friday also moved to freeze any financial assets found in the United States belonging to former Chechen President Zelimkhan Yandarbiyev. The U.N. terrorism committee recently added Yandarbiyev to a list of people with alleged links to al-Qaida.

The value of any assets that Yandarbiyev or Basayev may have in the United States was not known. By having their names added to the United States' list of specially designated global terrorists, both men not only have their assets blocked, but Americans also are prohibited from doing business with them.