Ten people were killed Friday in clashes between striking oil workers and police at a ceremony marking Kazakhstan's independence day in the western city of Zhanaozen, prosecutors said.

The buildings of the local administration, hotels and energy firm Uzenmunaigas facility were set on fire, prosecutor general Askhat Daulbayev was quoted as saying by the Interfax-Kazakhstan news agency.

"According to preliminary information, 10 people were killed as a result of the mass riots in Zhanaozen. There are also wounded, including police," he said in the capital Astana.

"The city hall, hotels, Uzenmunaigas offices were set on fire. Private and corporate property was also damaged, cars set on fire and ATMs robbed," he added.

Workers in Zhanaozen and other cities in the Mangistau region on the Caspian Sea have been striking for months for higher wages, in a highly unusual dispute for the Central Asian state which prides itself on its stability.

The exploration arm of state energy company Kazmunaigaz -- which owns Uzenmunaigas -- confirmed that "mass riots" had taken place in the city but insisted all its operations were working normally.

It said that Uzenmunaigas offices had been set on fire. "At the current moment, estimating the extent of the damage is not possible. This will be done later," it said, adding that all was being done to ensure the security of property.

Kyrgyzstan-based opposition Kazakh channel K-Plus broadcast a video of what appeared to be to start of the clashes when the oil workers in their work jackets stormed the stage that had been erected for the celebrations.

They tipped over speakers and appeared to push officials who had been preparing for the start of a concert. Dozens of police then appeared on the scene.

Daulbayev said the clashes were provoked by an attack by "hooligans" who assaulted police, turned over a Christmas tree and set a police bus on fire. He said they used bats.

The independent union Odak said in a statement that 3,000 strikers and their supporters had gathered on the central square of the city to show their discontent before the independence day ceremonies were due to take place.

Opposition news magazine Respublika said on its website that the protestors knocked down metal barriers. Prosecutors denied reports circulating on the Internet that shots had been fired.

"There are so many police that it seems they have come from all of Kazakhstan," one protestor named as Ayman Oungarbayeva told Respublika.

Veteran President Nursultan Nazarbayev had earlier, amid great pomp, inaugurated an Arch of Triumph in the capital Astana symbolising 20 years of the county's post-Soviet independence.

Kazakhstan was the last of 15 Soviet republics to declare its independence from the fading Soviet Union, on December 16, 1991.

Its vast energy reserves are hugely attractive for neighbouring energy-hungry China as well as for the West, which is keen to reduce Europe's dependence on Russia's hydrocarbons.