The former head of Kazakhstan’s counterintelligence and anti-terror agency has been arrested on charges of attempted government overthrow in the wake of violent protests that the president has blamed on foreign-backed terrorists.

The arrest of Karim Masimov was announced Saturday by the National Security Committee, which Masimov headed until he was removed this week by President Kassym-Jomart Tokayev.

Authorities say security forces killed 26 demonstrators in this week’s unrest and that 18 law-enforcement officers died. More than 4,400 people have been arrested, the Interior Ministry said Saturday.

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The protests in the Central Asian nation were the most widespread since Kazakhstan’s independence from the Soviet Union in 1991.

The unrest began in the country’s far west as protests against a sharp rise in prices for liquefied petroleum gas that is widely used as vehicle fuel. The protests spread to the country’s largest city, Almaty, where demonstrators seized and burned government buildings.

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At Tokayev’s request, the Collective Security Treaty Organization, a Russia-led military alliance of six former Soviet states, authorized sending about 2,500 mostly Russian troops to Kazakhstan as peacekeepers.

Some of the force is guarding government facilities in the capital, Nur-Sultan, which “made it possible to release part of the forces of Kazakhstani law enforcement agencies and redeploy them to Almaty to participate in the counter-terrorist operation,” according to a statement from Tokayev’s office.

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Tokayev said Friday that he had authorized security forces to shoot to kill those participating in unrest. On Saturday, there were no immediate reports of trouble in Almaty. Police dispersed a demonstration and detained people in the city of Aktau, while sporadic gunfire was heard in Kyzylorda, Russian news agency Sputnik said.

No details were given about what Masimov, the former security agency head, was alleged to have done that would constitute an attempted government overthrow. The National Security Committee, a successor to the Soviet-era KGB, is responsible for counterintelligence, the border guards service and anti-terror activities.

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Although the protests began as denunciations of the near-doubling of LPG prices at the start of the year, their spread and intense violence indicate they reflected widespread dissatisfaction in the former Soviet republic run by the same party for more than 30 years.

Many demonstrators shouted “Old man out,” a reference to Nursultan Nazarbayev, who was president from Kazakhstan’s independence until he resigned in 2019 and anointed Tokayev as his successor.

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Nazarbayev, who was given the title “ebasy,” or leader of the nation, retained substantial power as head of the National Security Council. But Tokayev removed him as council head amid this week’s unrest, possibly aiming at a concession to mollify protesters.

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Nazarbayev remained invisible during the chaos, but on Saturday his spokesman said Nazarbayev was in the capital and “calls on everyone to rally around the president of Kazakhstan to overcome current challenges and ensure the integrity of our country.”