MOSCOW - One person was killed in a shooting at a Unesco heritage site in Russia's volatile North Caucasus region of Dagestan, officials said on Wednesday.

The incident occurred on Tuesday night near the fortress in Derbent, which claims to be Russia's oldest city. "As a result of a shooting by the fortress one person was killed and 11 were injured," a spokeswoman for the local branch of the health ministry, Tatyana Abdullayeva, told AFP.

The injured, five of whom are in serious condition, have been taken to hospital for treatment, Abdullayeva added.

An unnamed source in law enforcement told the RIA Novosti news agency that the slain victim was employed by the Federal Security Service (FSB). Another FSB employee was also injured, according to the source. Police official Magomed Taymuradov told AFP the incident occurred near Derbent's historic citadel - declared a UNESCO World Heritage site in 2003 - and that security forces were searching for suspects.

The Kremlin is fighting a deadly insurgency against Islamist rebels in the largely Muslim North Caucasus, with unrest particularly intense in Dagestan.

Dagestan leader Ramazan Abdulatipov told Interfax news agency the attack could have been staged by "bandit groups" that "continue to take vengeance for the peace and tranquility the people of Derbent live in".

At least 118 people were killed in Dagestan between January and November as a result of the conflict, according to the Kavkazsky Uzel news portal, which monitors militancy in the North Caucasus.

Islamists in the North Caucasus have previously been united under a local Caucasus Emirate organisation, but are now increasingly flocking to the Islamic State group, which in June declared it had established a franchise there.

Syria's Al-Qaeda affiliate Al-Nusra Front has called on militants from the Caucasus to stage attacks in Russia in response to Moscow's bombing campaign in the country.