The group was ambushed in Chechnya's notorious mountain region of Itum Kale.

"Four were killed and one soldier was taken hostage after a gun battle between the two sides," a spokesman for the Russian Interior Ministry said.

"They had gone there to check out an explosion at the school," the spokesman added.

About 60,000 Russian servicemen remain subject to daily attacks in the Kremlin's second post-Soviet drive to crush the region's separatists.