The former Soviet republic of Uzbekistan, which is helping the United States in the campaign against terrorism in neighboring Afghanistan, has agreed to clean up and place tighter controls on stockpiles of anthrax and other biochemical weapons.

U.S. officials said the agreement was initialed Monday in Tashkent, the capital, with U.S. ambassador John Herbst. It follows similar accords reached with Russia, Ukraine and Kazakstan.

The hazardous material was stored during the Soviet period on a remote island in the Aral Sea, which is drying up and is considered an environmental threat, a senior U.S. official, speaking on condition of anonymity, told The Associated Press.

One of the biggest problems facing the United States after the dissolution of the Soviet Union in 1991 was safeguarding nuclear weapons stockpiles and biological and chemical weapons. Uzbekistan was a Soviet republic that gained its independence in the breakup.

Earlier, Ukraine and Kazakstan agreed to rid themselves of nuclear weapons. But concerns remained over biological and chemical weapons and over Soviet nuclear stockpiles. The fear is that "loose nukes" or other arms could be seized by or sold to terrorists.