At least four policemen were killed and four others injured on Sunday when they "foiled an attempt" by a suicide bomber to attack a concert hall in the capital of Chechnya, the Russian interior ministry told AFP.
The attacker blew himself up outside the hall where thousands were gathering for a concert to mark Grozny City Day in the regional capital, a ministry spokesman said.
He triggered the explosives after police securing the hall tried to inspect the man's identity papers, the spokesman added.
Medical sources cited by the Interfax news agency said the blast killed five police and injured 12.
The bombing took place several hours before the scheduled start of the concert, which also coincided with the birthday of strongman regional president, Ramzan Kadyrov.
"At the cost of their lives, the police saved the lives of thousands of people," said Russian Interior Minister Vladimir Kolokoltsev, quoted by state news agency TASS.
Kadyrov said the bomber "wanted to ruin people's joy on their day of celebration, but he has not succeeded," according to the news agency Ria Novosti.
Following a failed uprising against the Russian government in 1994-1996, the Chechen separatist movement became increasingly radical, evolving into a violent Islamist insurgency in the 2000s.