A senior U.S. diplomat will hold talks with Russian officials on Tuesday about opening up new supply routes across Russian territory to NATO forces in Afghanistan, the U.S. embassy said.

The talks come less than a week after Kyrgyzstan announced it will close a U.S. airbase on its territory that provides logistical support by air to U.S. troops fighting the Taliban in nearby Afghanistan.

Russia has signalled readiness to expand cooperation in supplying non-military equipment to U.S. forces and other NATO contingents in Afghanistan. Such shipments would also have to pass through Kazakhstan and Uzbekistan to reach the conflict zone.

Supply routes through Pakistan have become increasingly vulnerable to militant attacks over the last year.

"The Deputy Assistant Secretary of State, Patrick Moon, who is responsible for Afghanistan, is in Moscow and he is going to be engaged in discussions with Russian officials on NATO-Russia transit arrangements," a U.S. embassy spokesman said.

Russia does not have a formal agreement with NATO, but has agreed to allow transit non-military supplies, for example building materials, to Afghanistan.

Moon's talks will continue on Wednesday and will also touch on other issues where the United States is seeking to enlist greater international assistance to support Kabul's government against a resurgent Taliban.

"The provision of military and other assistance to the Afghans, counter-narcotics and counter-terrorism will also be discussed," said the embassy spokesman.

Kyrgyzstan's President Kurmanbek Bakiyev announced the closure of the Manas airbase on Feb. 3 in Moscow, hours after securing $2 billion in Russian aid. Moscow denies any link between the two announcements.

U.S. President Barack Obama is widely expected to approve plans soon to deploy up to 17,000 additional combat troops to Afghanistan.

U.S. Defense Secretary Robert Gates on told U.S. senators on Jan. 27 the war in Afghanistan could be lost and said Obama had made it his top overseas military priority.

"There is little doubt that our greatest military challenge right now is Afghanistan," said Gates.