ALMATY — Kazakhstan is prosecuting four senior police officers for using excessive force against rioters in an oil town where 17 people were killed in some of the country's worst violence in decades.


A regional deputy police head who coordinated the action in Zhanaozen is being sued for dereliction of duty, while three other senior officers will stand trial for abuse of power, the office of Kazakhstan's prosecutor general said.


A seven-month labor dispute between fired oilmen and their employers erupted into fierce clashes with police in the western oil city of Zhanaozen on Dec. 16. Officially, 16 people were killed on that day and another person died in clashes in a nearby village the following day.


The United States and the European Union have expressed concern about the violence and have urged Kazakhstan to conduct a transparent investigation into the riots.


The prosecutor general's office said, in general, the police had acted legally, resorting to the use of weapons after "a group of sacked oilmen and hooligan youths committed mass disorder."


"However, in some cases, the use of weapons and other special devices by the police was disproportionate, and the response ... was inappropriate to the actual threat," prosecutors said in a statement posted on their website.

"As a result of this abuse of power, they used weapons illegally, which led to the death and wounding of people."

A police spokesperson was unavailable for comment.

An amateur video, apparently taken on a mobile phone from an apartment window in the town and shared widely on the Internet, showed police shooting at fleeing protesters. There was no way of independently verifying the video's authenticity.

The riots broke out on the 20th anniversary of Kazakh independence from the Soviet Union and have become the most serious challenge to President Nursultan Nazarbayev's more than two decades in power. The former Communist party boss has stressed stability and ethnic harmony as his main priority.

"One of the main reasons for the disorder was the action of certain individuals to persuade sacked workers to continue the protest and their standoff with the authorities," it said.

Prosecutors accused the unregistered anti-Nazarbayev Alga! party of instigating the protests, saying it had been among those fomenting "social hatred." An Alga! spokesperson was unavailable for comment.

U.S.-based and local human rights groups called on Wednesday for the release of opposition activists and a newspaper editor detained this week. Prosecutors accuse them of being linked to the riots.

Those detained include Alga! leader Vladimir Kozlov and Igor Vinyavsky, editor of Vzglyad newspaper.

Nazarbayev, a 71-year-old former steelworker who has overseen market reforms but brooks no dissent, has sacked the heads of state oil firm KazMunaiGas and its London-listed subsidiary for mishandling the labor dispute with oilmen.

He has also sacked his billionaire son-in-law, Timur Kulibayev, one of Kazakhstan's richest and most influential people, from the post of head of sovereign wealth fund Samruk-Kazyna.

Prosecutors said the current and former mayors of Zhanaozen had embezzled funds earmarked for the oil city's social projects under the sponsorship of local oil firms.

Criminal proceedings have been launched against several oil company officials charged with large-scale embezzlement.