Russian authorities said on Wednesday that two explosive devices were detonated the previous evening on a main road near the city of Kaspiysk in southwestern Russia - around 20 kilometers (12.4 miles) south of the provincial capital Makhachkala.

"Two cars were blown up, the type of explosive device has not been established yet," local police spokeswoman Fatina Ubaydatova said.

"As a result, one policeman was killed and one was injured, according to preliminary information," she added.

Within hours of the attack, the Aamaq news agency, which is affiliated with IS, said the militant group were behind the blast, claiming that 10 security officers had been killed.

Dagestan remains one of Russia's most unstable regions. It has long been battling radical Islamist militants, linked to an Islamic insurgency, that spread through the mainly Muslim Caucasus region in the wake of two separatist wars in neighboring Chechnya in the 1990s.

Kremlin critics say the region's widespread poverty and corruption has helped to fuel religious extremism in the province, which also saw similar attacks on police in February.