Bomb kills four at theatre in southern Russia

STAVROPOL, Russia (Reuters) - At least four people were killed and 13 injured on Wednesday when a bomb exploded outside a theatre in the SOUTHERN (SO.NY)Russian city of Stavropol just before the start of a Chechen dance show, officials said.

Police are investigating if the blast was a "terrorist attack" the head of the city's emergencies department told Interfax news agency.

The ethnically Russian Stavropol region, which borders the violence-racked Muslim republics of the North Caucasus, has been hit by Islamist attacks in the past, but not in recent years.

Islamist rebels have vowed in recent months to expand their campaign of shootings and bombings to Russian cities. Suicide bombers on the Moscow metro in March killed 40 in the worst attack on the Russian heartland since 2004.

The Stavropol bomb was detonated minutes before the start of a concert by a celebrated Vainakh dance troop from Chechnya, a spokeswoman for the prosecutors office said.

"At least three women died in the explosion and a young man later died of his injuries," she said.

Two bodies covered in white sheets lay near the exit of the Stavropol Concert Hall, which was sealed off by police.

"This is an unprecedented, brutal provocation," said Stavropol Region Governor Valery Gayevsky, Interfax reported.

Russian President Dmitry Medvedev last year ordered that Stavropol Region be included in a new North Caucasus Federal District along with mainly-Muslim Chechnya, Dagestan and Ingushetia in a bid to tackle growing violence.

Medvedev's new envoy to the district, former metals executive Alexander Khloponin, on Wednesday called an emergency meeting to discuss the bomb, RIA reported.

Stavropol city is around 350 kilometres (220 miles) northwest of Chechnya's local capital Grozny. It has largely escaped Islamist insurgent attacks, but the surrounding region has seen some of the deadliest attacks in the long-running conflict.

Chechen rebels seized hundreds of hostages in a hospital in the Stavropol Region town of Budyonnovsk in 1995 and more than 100 died during the rebel assault and a botched Russian commando raid.

In the last major attack, 7 Russian policemen and 12 gunmen were killed when special forces stormed houses to fight rebels holed up in a village near the city in 2006.

(Writing by Conor Humphries; Editing by Matthew Jones)