Dozens of protesters have been killed in Kazakhstan in attacks on government buildings and at least a dozen police officers have died, including one who was found beheaded, authorities said.

Police spokeswoman Saltanat Azirbek said there were attempts to storm buildings in the country’s largest city, Almaty, during the night and that “dozens of attackers were liquidated”.

The reported attempts to storm the buildings came after widespread unrest in the city on Wednesday, including the seizure of the mayor’s building, which was set on fire.

State news channel Khabar-24 cited the city commandant’s office as saying that another 353 law enforcement officers were injured in addition to the 12 killed.

Kazakhstan is experiencing the worst street protests the country has seen since gaining independence three decades ago.

Earlier, a Russia-led military alliance said it will send peacekeeping forces to Kazakhstan after the country’s president asked for help in controlling the protests which were sparked by a rise in fuel prices but escalated sharply.

Police have clashed repeatedly with demonstrators in recent days, deploying water cannons in the freezing weather, and firing tear gas and concussion grenades.

President Kassym-Jomart Tokayev appealed to the Collective Security Treaty Organisation (CSTO), a Moscow-based alliance of six former Soviet countries, for assistance.

Hours later, the CSTO’s council approved sending an unspecified number of peacekeepers, said Armenian Prime Minister Nikol Pashinyan, the council’s chairman.

Mr Tokayev earlier vowed to take harsh measures to quell the unrest and declared a two-week state of emergency for the whole country, expanding one that had been announced for both the capital of Nur-Sultan and Almaty that imposed an overnight curfew and restricted movement into and around the urban areas.

The government resigned in response over the unrest.

Kazakh news sites became inaccessible late in the day, and the global watchdog organisation Netblocks said the country was experiencing a pervasive internet blackout. The Russian news agency Tass reported that internet access was restored in Almaty by early Thursday.

Although the protests began over a near-doubling of prices for a type of liquefied petroleum gas that is widely used as vehicle fuel, their size and rapid spread suggested they reflect wider discontent in the country that has been under the rule of the same party since gaining independence from the Soviet Union in 1991.

Mr Tokayev claimed the unrest was led by “terrorist bands” that had received help from unspecified other countries. He also said rioters had seized five airliners in an assault on Almaty’s airport, but the deputy mayor later said the airport was working normally.

Kazakhstan, the ninth largest country in the world, borders Russia to the north and China to the east and has extensive oil reserves that make it strategically and economically important.

Despite those reserves and mineral wealth, discontent over poor living conditions is strong in some parts of the country.