A key Kazakh security figure who was recently sacked from his position was detained over treason charges amid raging protests that crippled the Central Asian nation.

The National Security Committee, or KNB, said in a statement that its former chief Karim Masimov had been detained on Thursday after it launched an investigation into charges of high treason.

"On January 6 of this year the National Security Committee launched a pre-trial investigation into high treason," the statement said.

"On the same day, on suspicion of committing this crime, former chairman of the KNB K.K. Masimov was detained and placed in a temporary detention center, along with others."

Masimov, a close ally of Kazakhstan's founding President Nursultan Nazarbayev, was sacked from his post as head of the KNB earlier this week after protesters in Kazakhstan's largest city Almaty stormed government buildings.

Yermek Sagimbayev, previously head of State Security Service, was appointed to head the committee, which is the local successor to the Soviet KGB.

Masimov served as minister and deputy prime minister before getting appointed as premier for two stints between 2007 to 2012 and 2014 to 2016. Since then, he headed the KNB and has also served as head of the presidential administration under Nazarbayev.

Nazarbayev, 81, was the longest-serving ruler of an ex-Soviet state until he turned over the presidency to Tokayev in 2019. His family is widely believed to have retained influence in Nur-Sultan, the purpose-built capital that bears his name.

The move to detain Masimov comes amid accusations from a former advisor to Nazarbayev, who claims that the protests couldn't have spread and rioters couldn't have occupied key government buildings if high-ranking officials had not paved the way.

Yermuhammet Yertysbayev told Kazakh broadcaster Habar-24 that KNB had overlooked militant camps in mountainous areas, describing it as a crime against the state, according to remarks carried by the Anadolu Agency (AA).

Yertysbayev claims that before protesters took control of the Almaty Airport, all security forces were ordered to retreat from the area. He also said that the KNB building, the most secure place in the country, was quickly overrun by "terrorists."

Protests spread across the nation of 19 million this week in outrage over a New Year increase in prices for liquid petroleum gas (LPG), which is used to fuel many cars in the country.

Thousands took to the streets in Almaty and in the western province of Mangystau, saying the price rise was unfair given oil and gas exporter Kazakhstan's vast energy reserves.

The protests soon evolved into riots, with Tokayev accusing foreign-coordinated "terrorists" of taking part in an attempt to overthrow the government. More than 20 security personnel and dozens of rioters and protesters were killed in clashes.

A statement by the Kazakh Interior Ministry released Saturday said that a total of 4,266 suspects, including nationals from neighboring countries, were detained.

After several days of violence, security forces appeared to have reclaimed the streets of Kazakhstan's main city by Friday. Tokayev said he had ordered his troops to shoot to kill to put down a countrywide uprising.

At Tokayev's invitation, the Russia-led military alliance Collective Security Treaty Organization (CSTO) has been deployed at a time of high tension in East-West relations. Russia and the United States are gearing up for talks next week on the Ukraine crisis.