MOSCOW Russian President Vladimir Putin ordered security forces to be on high alert on Thursday to protect against attacks by militants ahead of next year's Winter Olympics in Sochi.
Russia, which this week hosts the G-20 meeting of major world economies, is battling an Islamist insurgency in the Caucasus region which grew out of two separatist wars in its Chechnya province since the fall of the Soviet Union.
In Russia's Caucasus province of Dagestan, a suicide bomber killed three policemen on Thursday, detonating explosives when police stopped his car for a routine documents check on the outskirts of the city of Khasavyurt.
Police later killed six militants in a shootout nearby, Russia's Anti-terrorism Committee (NAK)said.
Putin told senior officers from the Federal Security Service domestic intelligence agency that "all anti-terrorist forces should be at the highest level of alertness and readiness."
"The most important thing here is the protection of people's lives," he said in remarks broadcast on national television.
"It is necessary to provide reliable anti-terrorist protection of...large-scale public, international events soon to take place in our country," he said.
Putin, who rose to prominence by crushing the Chechen separatist rebellion, is seeking to boost Russia's prominence by hosting more high-profile international events such as the G-20 and the World Cup in 2018. He has ordered security officials to make sure both events are secure.
Next year's Olympics in Sochi have been declared a target by the Caucasus Emirate group, which claimed responsibility for a suicide bombing at Moscow's Domodedovo airport in January 2011 that killed 37 people. It also claimed two bombings of Moscow's metro system in 2010 that killed 40 people.
Militant violence in the Caucasus is rooted in two separatist wars fought in Chechnya in the 1990s until 2000. Since then it has spread to neighboring regions.
Dagestan, on the eastern edge of the Caucasus mountain chain, is hit by almost daily bomb attacks and shootings targeting policemen and officials.
It was unclear how many people were in the suicide bomber's car before he detonated the explosives, but the Interior Ministry said that the original target was likely in Khasavyurt.
"Police officers stopped the... car for a check. Behind the wheel was a terrorist suicide bomber," the ministry statement said. "When police officers walked up to the car, he detonated the explosive device."
One person remained unaccounted for and six police were taken to hospital, officials said.
Television showed pictures of the twisted wreckage of the car and police cars with its windows blown out near the security checkpoint, one of many in the restive region where police regularly check identity papers.
The Investigative Committee, a criminal investigation arm that answers only to Putin, said the explosion tore a hole almost four meters (13 feet) wide in the checkpoint building.
Human rights groups say the insurgency, led by self-styled emir of the North Caucasus Doku Umarov, is being driven by a volatile mix of religion, corruption and grievances against the strong-arm tactics of some local leaders against suspected militants and their families.
The suicide bombing followed a police raid on a Dagestani forest hideout that killed five militants earlier this week.
(Reporting by Thomas Grove; Editing by Jon Boyle)