By Gabriela Baczynska

MOSCOW (Reuters) - Russian security forces killed the leader of an Islamist insurgency in the North Caucasus during a raid on a house in the Dagestan region, the national Anti-Terrorist Committee (NAK) said on Monday.

Dagestan, from which convicted Boston Marathon bomber Dzhokhar Tsarnaev emigrated with his family to the United States in 2002, has become a hub of militant Islam in the North Caucasus.

Four other suspected militants were also killed with Aliaskhab Kebekov, also known as Ali Abu Mukhammad, after special forces surrounded the house in a suburb of the town of Buynaksk in southern Russia on Sunday, NAK said.

It released video footage showing the house exploding and a shootout followed by more blasts. The house is later seen in ruins, with the rubble ablaze.

The Kavkaz Centre website, which sympathizes with the militants, said Kebekov had been "martyred" in an "unequal battle" with state troops.

Kebekov, born in 1972, became the leader of the Caucasus Emirate group in early 2014 after Russian security forces killed his predecessor, Doku Umarov, who had been Russia's most-wanted man.

Two other senior Dagestani militants were among the dead, NAK also said, adding that a child had been allowed to leave but two women as well as the suspected militants had refused to come out during negotiations preceding the raid.

Kebekov's Caucasus Emirate was listed as a terrorist group by the United States in 2011 and is held responsible for several deadly bombings in Russia in recent years.

Moscow waged two 1990s wars on separatists in Chechnya, which borders Dagestan. It now faces an insurgency by militants who have proclaimed a caliphate in the North Caucasus, a patchwork of mainly Muslim provinces on Russia's southern rim.

Russian authorities have sounded an alarm over the insurgents' links with Islamic State (IS) and said some militants have ventured out to join the ranks of the ultra-radical group, which controls large swathes of Syria and Iraq.

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A North Caucasus expert and editor of the Caucasian Knot website, Grigory Shvedov, said the killing of Kebekov could strengthen the cause of more radical militants who broke ranks with him last December to shift allegiance to Islamic State.

Rights activists and Kremlin critics accuse Russia of using heavy-handed tactics in the North Caucasus that violate the law and increase resentment among locals. Russian authorities say the use of force is necessary to protect public safety.

(Editing by Timothy Heritage and Mark Heinrich)