BISHKEK, Kyrgyzstan - Kyrgyzstan's parliament will delay until next week a vote on a plan to close a key U.S. air base that supports American and NATO operations in Afghanistan, a senior official said Thursday.

The delay could allow time for the United States to try to continue negotiations over the Manas base, a vital component of American plans to expand military operations in Afghanistan and develop alternate supply routes after attacks on convoys in Pakistan.

Kyrgyz President Kurmanbek Bakiyev announced a decision this week to end the U.S. military presence in his impoverished Central Asian nation after securing billions of dollars in loans and aid from Russia. Moscow resents the American presence in a country that it regards as part of its traditional sphere of influence.

A parliamentary debate and vote on a government-sponsored bill calling for the closure of the base was initially expected Friday.

But the government's representative to parliament, Murza Kaparov, called on deputies to discuss the proposal "slowly at committee stage and in the political party groupings," which means the bill is unlikely to be voted on before a regular plenary session next Thursday. The reason for the postponement was not immediately clear.

Alisher Sabirov, a deputy with the pro-Bakiyev Ak Zhol party that dominates parliament, said the discussions would be delayed in line with the government's request.

Kyrgyz National Security Council chief Adakhan Madumarov said Bakiyev's decision would not be reconsidered and "there is no way back." But the delay appeared to raise a slim prospect of a breakthrough in U.S.-Kyrgyz talks over the base.

On Wednesday, the U.S. Embassy in Kyrgyzstan said that Washington had received no formal notification of the base's closure and that talks would continue despite Bakiyev's announcement.

Kyrgyz officials would not confirm whether further negotiations are expected.

The base, located with the Manas civilian airport near Kyrgyzstan's capital, is home to tanker planes that refuel warplanes flying over Afghanistan. It also supports airlifts and medical evacuation operations and houses troops heading into and out of Afghanistan. Kyrgyzstan and Afghanistan do not share a border.

Kyrgyzstan's government said the decision to close the air base was made because it has fulfilled its purpose of supporting military actions in Afghanistan. Authorities also cited growing popular discontent with the U.S. military presence.

Many analysts believe, however, that Kyrgyzstan is acting under pressure from Russia. Bakiyev has also said that his government is unhappy with the financial arrangements over the base.

In a visit to the base last month, Gen. David Petraeus, commander of U.S. operations in Afghanistan and Iraq, said the U.S. currently pumps $150 million into Kyrgyzstan's economy annually, including $63 million in rent for Manas.

Paul Quinn-Judge, Central Asia project director for the Brussels-based International Crisis Group, said the United States has been slow in addressing Kyrgyz demands for more.

"The Americans don't seem to be moving very fast on making a counterbid, if indeed they intend to do so," he said. "The first signs one can see is that they may be resigned to just closing the base and moving on."

Kyrgyz officials have not specified when the closure might take place, but the agreement under which the base was established in 2001 specifies that the United States must be given 180 days' notice.

The threat of closure comes at a time when increasing attacks on transportation depots and truck convoys in Pakistan have raised doubts about its ability to protect vital supply routes and have increased the need for alternative routes through Central Asia. Some 75 percent of U.S. supplies to Afghanistan currently travel through Pakistan.