By Mariya Gordeyeva and Tamara Vaal
ALMATY (Reuters) - Kazakhstan's former intelligence chief has been arrested on suspicion of treason, the state security agency said on Saturday, as the former Soviet republic cracks down on a wave of unrest and starts to assign blame.
The detention of Karim Massimov was announced by the National Security Committee which he headed until he was fired by President Kassym-Jomart Tokayev on Wednesday after violent protests swept across the Central Asian nation.
Tokayev's office said he had told Russian President Vladimir Putin in a phone call that the situation was stabilising.
"At the same time, hotbeds of terrorist attacks persist. Therefore, the fight against terrorism will continue with full determination," it quoted him as saying.
The Kremlin said Putin backed Tokayev's idea to convene a video call of leaders from the Collective Security Treaty Organisation (CSTO), under whose umbrella Russia and four other former Soviet republics have sent troops into Kazakhstan to help restore order. It was not clear when this would take place.
Dozens of people have been killed, thousands have been detained and public buildings across Kazakhstan have been torched over the past week in the worst violence experienced in the oil and uranium producer since it became independent in the early 1990s as the Soviet Union collapsed.
Tokayev has ordered his troops to shoot to kill to end what he has called attacks by bandits and terrorists.
He said on Friday the state had "slept through" instigators' preparations to launch attacks on the biggest city, Almaty, and across the country. Massimov's arrest indicated moves were under way against those deemed responsible.
Apart from heading the intelligence agency that replaced the Soviet-era KGB, Massimov was twice prime minister and worked closely with former President Nursultan Nazarbayev, the country's ruler for three decades until he turned over the presidency to Tokayev in 2019.
There were no details of the treason allegations. The security service said other officials were also detained, but did not name them.
On Friday, a pro-government politician said on television he had information that the security forces had been ordered to abandon Almaty airport so protesters could take it over. He said they had left a security building in the city undefended, enabling people to seize weapons.
It was not immediately possible to verify this account. The airport remains closed but is now under the control of Kazakh security personnel and Russian troops, according to Russia's defence ministry.
The demonstrations began as a response to a fuel price hike but swelled into a broad movement against Tokayev's Russian-backed government and 81-year-old Nazarbayev.
Tokayev removed Nazarbayev on Wednesday as head of the country's Security Council, a role in which he had continued to wield significant influence. Interfax news agency reported on Saturday that the council's deputy head had also been fired.
In Almaty, where security forces have reclaimed control of the streets since Friday, a Reuters reporter said occasional gunshots were heard on Saturday.
Some businesses began to reopen in the city as people ventured out to buy supplies, and queues formed at petrol stations.
Security forces patrolled the streets and set up checkpoints. The deputy mayor was quoted by Russia's RIA news agency as saying operations to purge the city of "terrorists and bandit groups" were still under way and citizens were advised to stay at home.
Zhumadin Patov, the deputy head of a public market in Almaty, said the checkpoints and petrol station closures had complicated food distribution in the city of about 2 million people.
"There is enough food in warehouses, but it cannot be delivered because of the checkpoints and lack of fuel," he said.
In the capital Nur-Sultan, Reuters filmed police stopping drivers at a checkpoint with armed soldiers nearby.
The interior ministry said more than 4,400 people had been detained since the start of the unrest. Tokayev announced a national day of mourning for Monday to commemorate those killed.
Access to the internet, which was been largely shut down in Kazakhstan for days, was still heavily disrupted on Saturday.
The deployment of the Russia-led CSTO military alliance at Tokayev's invitation comes at a time of high tension in East-West relations as Russia and the United States prepare for talks next week on the Ukraine crisis.
Moscow has deployed large numbers of troops near its border with Ukraine but denies U.S. suggestions it is planning an invasion, saying it wants guarantees that NATO will halt its eastward expansion.
Washington has challenged the justification for sending Russian troops to Kazakhstan and questioned whether what has been billed as a mission of days or weeks could turn into a much longer presence.
"One lesson of recent history is that once Russians are in your house, it's sometimes very difficult to get them to leave," Secretary of State Antony Blinken said on Friday.
Russia's foreign ministry called the remark offensive and said Blinken should reflect on the U.S. track record of military interventions in countries such as Vietnam and Iraq.
(Reporting by Olzhas Auyezov and Mariya Gordeyeva in Almaty and Tamara Vaal in Nur-Sultan; Additional reporting by Gabrielle Tétrault-Farber in Moscow; Writing by Mark Trevelyan; Editing by Pravin Char, Timothy Heritage and Helen Popper)