Uzbekistan's President Shavkat Mirziyoyev said today there were casualties among civilians and law enforcement officers after rare protests in the Central Asian country, and an exiled opposition politician said at least five people had been killed.

In a statement posted online, Mr Mirziyoyev said rioters had carried out "destructive actions" in the city of Nukus, capital of the northwestern Karakalpakstan region, by throwing stones, starting fires and attacking police.

"Unfortunately there are victims among civilians and law enforcement officers," he said. The statement did not specify the number and nature of the casualties.

An exiled opposition politician, Pulat Ahunov, said that, based on contacts with local sources and video evidence, at least five people had been killed. He said there were unconfirmed reports of dozens more dead.

Mr Ahunov said people were unable to move around and obtain more information because of a state of emergency imposed by the authorities.

Uzbekistan is a tightly controlled former Soviet republic where the government clamps down hard on any form of dissent.

It was the second outbreak of unrest in Central Asia this year, after Kazakhstan crushed mass protests in January and Russia and other former Soviet republics sent in troops to help the authorities restore order.

The protests in Uzbekistan were prompted by planned constitutional changes that would have stripped Karakalpakstan of its autonomous status. In an about-turn, the president dropped those plans yesterday.

Mr Ahunov, chairman of the opposition Berlik party, said from Sweden that he condemned the use of lethal force.

"The authorities, from the start, should have opted for dialogue and negotiations," he said.

He said he feared the potential for the situation to escalate into an ethnic conflict between Uzbeks and Karakalpaks, a minority group with their own language. Authorities had called a public meeting for Tuesday to discuss the situation, he added.

Kazakhstan said it was concerned by the events in Uzbekistan and welcomed moves by the authorities to stabilise the situation.

Steve Swerdlow, Associate Professor of Human Rights at the University of Southern California and an expert on the region, said Uzbekistan had long avoided discussing the concerns of ethnic minority groups.

"The government should engage as transparently as possible in this case on what has occurred, including on casualties and the use of force, allow independent media to report, and over the longer term conduct some difficult discussions with the local population about what concerns were at the heart of these mass protests," he said.