Uzbekistan's President Shavkat Mirziyoyev said on Sunday there were casualties among civilians and law enforcement officers after rare public protests in the country's northwestern Karakalpakstan province.

In a statement posted online, Mirziyoyev said rioters had carried out "destructive actions" in the city of Nukus, 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.

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

Hugh Williamson, Europe and Central Asia director at Human Rights Watch, said on Twitter: "There are unconfirmed reports of excessive force used by security personnel during protests in Nukus on July 1." He called for an investigation.

The foreign ministry of neighbouring Kazakhstan, whose government crushed violent protests in early January, said it was concerned by events in Uzbekistan.

"We welcome and support the decisions of the top leadership of Uzbekistan to stabilise the situation in the Republic of Karakalpakstan," the ministry said in a statement.

On Saturday Mirziyoyev dropped plans to roll back the province's autonomy after the protests, which his statement said had started on Friday.