The United States has taken delivery of its last shipment of downgraded uranium from Russia, signaling the end of a 20-year program to neutralize around 500 tonnes of the weapons-grade material, the White House said Tuesday.

"Today the United States and Russia are commemorating the completion of one of the most successful non-proliferation programs in our history," National Security Council spokeswoman Caitlin Hayden said in a statement.

The final shipment of low-enriched uranium arrived in the Maryland port city of Baltimore, Hayden added.

The fuel, which is destined for use in US nuclear plants, is the latest from a vast quantity contained in some 20,000 Russian warheads which were deactivated under the 1991 START treaty at the end of the Cold War.

The recycling and transfer of the uranium to the United States were formalized in a 1993 agreement.

The program -- named "Megatons to Megawatts" -- had helped provide 10 percent of all US electricity generated over the past 15 years, Hayden added.

"The United States and Russia remain strongly committed to building on this success, and will continue to collaborate across various fields of nonproliferation, nuclear security and nuclear research and development," Hayden said.

The agreement was halted at the initiative of Russia, which said the United States was not paying enough for the uranium, roughly equivalent to 10 billion barrels of crude. A much smaller quantity of uranium from decommissioned US weapons had also been used to produce energy.

The United States had sought to extend the agreement with Russia but Moscow refused.

Washington has paid close to $8 billion up until now for Russian uranium, according to the United States Enrichment Corporation (USEC), the government agency which provides fuel to power plants.

USEC has signed a new agreement with Russian consortium Techsnabexport, but fuel provided under the deal will be at market prices, USEC said in October.

The end of the post-Cold War deal comes at a time of tensions between the United States and Russia, who have sparred this year over Syria, a missile shield in Europe and the fate of US intelligence leaker Edward Snowden, who has been granted refuge in Moscow.