The United States said on Monday it was "deeply disturbed" by reports Uzbek authorities fired on unarmed demonstrators last week as they suppressed a rebellion in the former Soviet state that is a strategic ally of Washington. Secretary of State Condoleezza Rice also called for political reform in the Central Asian country, where autocratic President Islam Karimov has ruled since Soviet times and the United States has a major air base supporting Afghan operations, Reuters reported. "We are deeply disturbed by the reports that the Uzbek authorities fired on demonstrators," State Department spokesman Richard Boucher told reporters. "We certainly condemn the indiscriminate use of force against unarmed civilians and deeply regret any loss of life." The comments were the strongest from the United States since a blood bath in the town of Andizhan on Friday when troops killed 500 protesters, according to some estimates. Rice, who has sought to promote democracy in former Soviet states, said Uzbekistan had a political system that was "too closed." "We have been encouraging the Karimov government to make reforms, to make the system more open, to make it possible for people to have a political life," said Rice, who spoke to reporters as she flew home after a trip to Iraq. Her remarks followed criticism from the European Union, which said the protests came as a result of the government's failure to respect human rights and the rule of law.