MOSCOW: Russia said it had killed on Wednesday a militant wanted for the 2010 bombing of an outdoor market in the North Caucasus, a restive region where three late-night bomb blasts and two gun battles highlighted a dragging insurgency.

More than a decade after Moscow reasserted federal control over Chechnya following two separatist wars, it is still struggling to extinguish an insurgency seeking to carve out an Islamic state in the mainly Muslim regions in Russia's south.

Security forces shot dead Sultangery Khashagulgov and one of three brothers suspected of staging an attack on a busy market in the North Ossetia capital of Vladikavkaz that killed 19 people in 2010, a law enforcement source told Interfax.

Khashagulgov, 48, a businessman and former minister in charge of construction in the province of Ingushetia, was killed when he open fired on security forces who attempted arrest him at his home in the regional capital of Nazran, it said.

Security forces had earlier detained Khashagulgov's brothers Isa and Yakuba.

Militant violence has spread from Chechnya to the neighbouring provinces of Dagestan and Ingushetia, where insurgents stage near daily attacks.

Three bombs targeted law enforcement officials in Dagestan late on Tuesday, local news agencies reported. No one was killed in the attacks. A police officer was in hospital with gunshot wounds after a separate late-night shooting.

Gunmen also opened fire late on Tuesday on the main offices of the Investigative Committee, the government's criminal investigation arm, in Makhachkala, Dagestan's provincial capital. No-one was reported hurt.

Restoring Moscow's writ in the Caucasus defined the meteoric rise of Vladimir Putin from little known spy chief to president, and security is a priority with the 2014 Winter Olympics taking place at the western end of the Caucasus mountain range.