Wounded victims filled the hospitals of a western Kazakh oil city on Saturday and some oil workers stayed at home, fearing for their safety after Independence Day celebrations turned into the deadliest violence in the ex-Soviet state's recent history.

At least 10 people were killed when riot police clashed on Friday with a crowd in the city of Zhanaozen, centre of protests by nearly 1,000 oil workers sacked by state-controlled KazMunaiGas Exploration Production.

The head of a local trade union told Reuters sporadic shooting had been heard throughout the night in Zhanaozen, a city of 90,000 around 150 km (95 miles) inland from the Caspian Sea. Power and internet communication had been cut off, he said.

The hospitals in Zhanaozen are all full and they are bringing the wounded to Aktau, civilians and policemen alike, said Kenzhegali Suyeov, chairman of the Aktau independent union.

They have all kinds of wounds, from gunshot wounds to stab wounds and blunt traumas, he said, sourcing his information to people who had driven from Zhanaozen to Aktau, the regional capital. All roads into Zhanaozen had been blocked, he said.

Public protests are rare in Kazakhstan, Central Asia's largest economy and oil producer, where President Nursultan Nazarbayev has ruled for more than 20 years and has overseen massive foreign investment, mainly in oil and gas.

The clashes marred celebrations across the rest of Kazakhstan to mark the 20th anniversary of independence from the Soviet Union and were a shock to a government that has prized stability and economic growth over democratic freedoms.

The clashes began when sacked oil workers and sympathetic citizens stormed a stage erected for an Independence Day party, toppling sound equipment and later setting fire to the city hall and the headquarters of KazMunaiGas EP's local production unit.

Prosecutor-General Askhat Daulbayev said 10 people had been killed in clashes after law officers were attacked by hooligans armed with guns. He did not say who had been killed or how.

Reports on social networking websites said the death toll was much higher than 10 and that police had opened fire. These reports could not be verified independently. New York-based Human Rights Watch said at least some mobile phone and internet access had been shut down in the city.

Interior Minister Kalmukhanbet Kasymov, who flew to Zhanaozen, said around 70 people had been arrested in the city. He said 75 people had been taken to hospital and six police officers were among the injured, Interfax reported.

The disorder in Zhanaozen has been suppressed. The situation in the city is calm and nobody is on the square, Interfax quoted Kasymov as saying.

CARNAGE

Opposition activist Gulzhan Yergaliyeva was among about 100 people attending a ceremony in the commercial capital Almaty to commemorate Kazakhs killed in clashes with Soviet troops and police in December 1986.

Yesterday, exactly 25 years later, the same tragedy was repeated, she said.

Thousands of KazMunaiGas EP workers began a strike in May demanding better pay and conditions. The company, calling the strikes illegal, sacked 989 workers and has said production will fall 8.5 percent short of its target this year.

The London-listed company said the Interior Ministry was providing armed security at oil production facilities and some workers had failed to show up for the night and morning shifts due to security concerns. A round-the-clock shift by workers on site was maintaining daily output levels.

KazMunaiGas EP, majority owned by state oil and gas company KazMunaiGas, has said 2,500 people were on strike at the height of the dispute. Representatives of the striking workers have put the maximum number at almost 16,000.

Its Uzenmunaigas subsidiary near Zhanaozen employs 9,000 people, but the strikes were not confined to this unit alone. Workers at the Karazhanbasmunai field, a joint venture with Chinese state-owned company CITIC, also downed tools in May.

For seven months, those striking workers were standing in the scorching sun, in the rain, and wind and snow, and the authorities would not start a dialogue with them, said Bolat Abilov, a leader of the opposition Social-Democratic Party.

Around 20 protesters broke off from the memorial service and attempted to march to the city headquarters of the ruling Nur Otan political party. Riot police detained around half of them.

KazMunaiGas EP's London-traded stock closed down 4.0 percent on Friday, versus a decline of only 0.4 percent in the wider oil and gas sector.

(Additional reporting by Mariya Gordeyeva; editing by Angus MacSwan)