* Militants opened fire on security forces, officials say
* Two brothers killed had attacked checkpoint - committee
MOSCOW, April 8 (Reuters) - Russian security forces killed four militants but lost one of their own in a firefight on Monday in Ingushetia, where an Islamist insurgency has spread from the neighbouring region of Chechnya, officials said.
More than a decade after Moscow reasserted federal control over Chechnya following two separatist wars, it is still struggling to contain violence by insurgents seeking to carve out an Islamic state in nearby mainly Muslim provinces.
Russia's Anti-Terrorism Committee (NAK) said the four militants were killed after they opened fired on security forces carrying out an operation in the village of Dolakovo near the provincial capital of Narzan.
"Two pistols, one of them with a silencer, and two homemade grenades were found at the site of the clashes," NAK said in a statement.
One security officer was killed in the clashes, it said.
NAK identified two of those killed as brothers, Adam and Khalas Ozdoyev, who it said were responsible for an attack on a checkpoint in which three policemen were killed last October.
Bomb attacks on police checkpoints and shootings targeting officials are a frequent event in Russia's Muslim, southern regions of Igushetia, Dagestan and Kabardino-Balkaria, near Chechnya.
Security risks in the region are in the spotlight ahead of the 2014 Winter Olympics, which Russia will host in the Black Sea resort of Sochi, at the western end of the Caucasus mountains. (Reporting By Alissa de Carbonnel; Editing by Michael Roddy)