The action followed US and international demands for an investigation into the reported killings of hundreds of people by Uzbek security forces during a crackdown on demonstrations at Andijan on May 13.

The restrictions were imposed within the past couple of weeks, said Bryan Whitman, a Defense Department spokesman, who added that the US Central Command has made temporary adjusgements in operations affected by the action.

"There have been some limitations placed on the use of the airfield by Uzbekistan," said Whitman.

Whitman declined to provide details but confirmed that the restrictions include a halt to night operations at the base, a key logistics hub to resupply US and NATO-led troops in Afghanistan.

The Washington Post reported that the Central Command has moved HC-130 search and rescue and tanker aircraft to Bagram Air Base in Afghanistan because of the ban on night flights.

The Post said the Uzbeks also put restrictions on C-17 cargo flights into Kharshi-Khanabad, or K-2 as the military calls it, forcing the command to route those flights through Manas air base in Kyrgyzstan.

Whitman stressed the importance of K-2 to US operations in Afghanistan.

"But at the same time the United States government has called on the Uzbeks to conduct a full and transparent inquiry into the Andijan incident. That is the stated policy of the United States government," he said.

However, the Bush administration appears conflicted over how much pressure to put on the regime of Uzbek President Islam Karimov as it attempts to reconcile its goal of supporting democratic movements with its military interest in maintaining access to a vital base near Afghanistan.

The Post reported Tuesday that US Defense Secretary Donald Rumsfeld joined Russia in blocking a call by NATO defense ministers last week for an independent, international inquiry of the killings.

Trent Duffy, a White House spokesman, on Tuesday denied any rift within the administration, insisting that the administrtion was speaking "with one voice" on the issue.

"The administration has made its view known that it wants the government of Uzbekistan to allow a credible, independent international investigation into the events at Andijan," he said.

Karimov, whose regime has been accused of engaging in torture and systematic human rights abuses, has so far ignored calls for an outside investigation.

Uzbekistan said 173 people, including security forces, died in the unrest at Andijan. But human rights organizations say between 500 and 1,000 people were killed by Uzbek security forces who opened fire on unarmed civilians in the town square.

General John Abizaid, head of the US Central Command, said last month that US military scaled back its operations at the base in Uzbekistan after the incident because of what he said was "a potential change in the security situation."

Republic Senator John McCain, who briefly visited Uzbekistan two weeks ago, said Uzbekistan had been genuinely helpful in the war on terrorism and in particular at the height of the US-led offensive that toppled the Taliban regime in AFghanistan.

But, writing in the Financial Times this week, he said the killings were only the latest and most dramatic example of internal repression.

"If this trend continues, the US has no choice but to re-evaluate all aspects of its relationship with Uzbekistan, and this includes our military relations. While we review our policy, we should suspend any talk of a long-term basing arrangement and look very critically at our continued presence at the Karshi-Khanabad air base," he said.

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