Police in the main city Almaty said they had killed dozens of rioters overnight. State television said at least 13 members of the security forces had died, including two found decapitated. The interior ministry said 2,000 people had been arrested.

After a night of running confrontations between protesters and troops on the streets, a presidential residence in the city and its mayor's office were both ablaze, and burnt out cars littered the city. 

Military personnel regained control of the main airport, seized earlier by protesters. But Thursday evening saw renewed battles in Almaty's main square, occupied alternately by troops and hundreds of protesters throughout much of the day.

The Russian deployment was a gamble by the Kremlin that rapid military force could secure its interests in the oil and uranium-producing Central Asian nation, by swiftly putting down the worst violence in Kazakhstan's 30 years of independence.

TASS news agency quoted witnesses as saying people had been killed and wounded in the new gunfire. The shooting stopped again after nightfall.

Internet was shut down across the country and while the full extent of the unrest was not immediately clear, it was unprecedented in a country ruled firmly since Soviet times by leader Nursultan Nazarbayev, 81, who has held on to reins of power despite stepping down three years ago as president.

"ATTACK ON OUR CITIZENS"

Nazarbayev's hand-picked successor, President Kassym-Jomart Tokayev, called in forces from ally Russia overnight as part of a Moscow-led military alliance of ex-Soviet states. He blamed the unrest on foreign-trained terrorists who he said had seized buildings and weapons.

"It is an undermining of the integrity of the state and most importantly it is an attack on our citizens who are asking me... to help them urgently," he said.

Moscow said it would consult with Kazakhstan and allies on steps to support the Kazakh "counter-terrorist operation". It said the uprising was foreign-inspired. Neither Kazakhstan nor Russia provided evidence to support the assertion of foreign involvement.

The secretariat of the Russian-led Collective Security Treaty Organisation said advance units of Russian paratroopers had reached Kazakhstan and had "already begun to fulfil their assigned tasks".

As well as the Russians, the force would include troops from Belarus, Armenia, Tajikistan and Kyrgyzstan, it said, without disclosing the overall size of the force. 

The uprising, which began as protests against a New Year's Day fuel price hike, swelled on Wednesday, when protesters stormed and torched public buildings in Almaty and other cities. They chanted slogans against Nazarbayev, and in at least one city looped ropes around a statue of him, trying to pull it down.

Tokayev initially responded by dismissing his cabinet, reversing the fuel price rise and distancing himself from his predecessor, including by taking over a powerful security post Nazarbayev had retained.

But the actions failed to mollify crowds who accuse Nazarbayev's family and allies of amassing vast wealth from oil and minerals while the nation of 19 million remained poor.

Nazarbayev stepped down in 2019 as the last Soviet-era Communist Party boss still ruling a former Soviet state. But he and his family kept posts overseeing security forces and the political apparatus in Nur-Sultan, the purpose-built capital bearing his name. He has not been seen or heard from since the unrest began.

The swift arrival of Russian troops demonstrated the Kremlin's strategy of deploying force to safeguard its influence in the ex-Soviet Union. Since late 2020, Moscow has shored up the leader of Belarus in the face of a popular uprising, intervened to halt a war between Azerbaijan and Armenia, and, to the West's alarm, massed forces again near Ukraine, which Russia invaded eight years ago.

Controlling Kazakh protesters with Russian troops "will not look great for Moscow," tweeted economist Tim Ash, who specialises in the region.

Western countries called for calm. Neighbour China called the events an internal matter for Kazakhstan.

Under Nazarbayev, Kazakhstan gained a reputation for stability, attracting foreign investment. Though political opposition was curtailed, the state was regarded as less repressive and volatile than its ex-Soviet Central Asian neighbours.

Kazakhstan's long-dated dollar-denominated sovereign bonds have plunged, losing around 7 cents since the start of the week. ,

An OPEC+ oil producer, Kazakhstan is also the top global producer of uranium. The unrest prompted an 8% jump in the price of the metal and a surge in share prices of uranium producers elsewhere. Miner Kazatomprom said it was operating normally with no impact on output or exports. read more

Oil producers and pipeline companies also reported no cuts.

The country is the world's second-largest miner of bitcoin after the United States. Bitcoin's "hashrate" - the measure of computing power of machines plugged into its network - dropped by over 10% on Wednesday after Kazakhstan's internet was shut off, according to crypto mining firm BTC.com.

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