But the removal also coincided with escalating criticism of President George W. Bush by his democratic rival in the November 2 election, Senator John Kerry, who has accused the White House of being lax in confronting the spread of nuclear material around the world.

Energy Secretary Spencer Abraham said Monday the one-day operation, implemented last Thursday, was crucial for enhancing international security.

"The recovery, return and eventual elimination of this highly-enriched uranium are an important milestone in our campaign to reduce this dangerous material worldwide," he said in a brief statement.

The operation targeted 11 kilograms (24.2 pounds) of enriched uranium fuel, including highly-enriched uranium that could be used for manufacturing nuclear weapons, that was brought to Uzbekistan during Soviet times, officials said.

The material was used in a Russian-designed, 10-megawatt, multi-purpose research reactor installed outside the Uzbekistan capital, Tashkent, the officials pointed out.

During the operation, the uranium was loaded inside two special Russian containers, taken to an airport outside of Tashkent and airlifted under guard to a secured nuclear facility in the Russian city of Dmitrovgrad.

The Russians have agreed to blend down the material into low-enriched uranium that can be used in power plants.

The whole procedure, including the loading of the fuel in the canisters, was monitored by inspectors from the International Atomic Energy Agency and US technical experts, the officials said.

As part of the fuel removal deal, the Uzbek government also has agreed to convert its research reactor to low-enriched uranium fuel that cannot be used in weapons production.

The Dmitrovgrad facility is a partner in a US-financed initiative designed to stem the spread of nuclear materials and technology around the world, according to the Energy Department.

"It was only with the strong cooperation of the Uzbeks and Russians that we were able to successfully complete this important international security mission," Abraham pointed out.

The operation marked the fifth shipment of uranium to Russia from its Soviet-era allies and partners.

Over the past year, the United States repatriated a total of 48 kilograms (105 pounds) of highly-enriched uranium to Russia from Romania, Bulgaria and Libya, according to US officials.

An equal amount of fuel was brought back from a research reactor near Belgrade, Serbia, in August 2002.

The removal comes as Uzbekistan is facing escalating violence local authorities blame on Muslim extremists associated with Hizb ut-Tahrir, a group aspiring to create an Islamic state in Central Asia.

In July, suicide bombers set off explosives outside the US and Israeli embassies in Tashkent, killing four Uzbek security guards.

Thirty-three people went on trial in Uzbekistan last week on charges of carrying out a string of terror attacks in March and April that left at least 47 people dead.

But Abraham also added discernible political overtones to his announcement.

He recalled the recent breakup of the Pakistani-based, A.Q. Khan nuclear smuggling network and Libyas decision to give-up its nuclear weapons program, insisting that the US administration's accomplishments in the field of nuclear nonproliferation have been "significant."

The remarks appeared to counter Kerry's oft-repeated charge that there was less nuclear weapons materials secured in the two years following the September 11, 2001, attacks than in the two years before.