MOSCOW — Five members of a banned militant group have been arrested in the southern Russian town of Nalchik, where a homemade bomb packed with shrapnel has been defused, the Russian National Anti-terrorism Committee said on Saturday.

Nalchik, in the foothills of the Caucasus mountains, is about 190 miles from the town of Sochi, host of next month's Winter Olympics, which Islamist militants have threatened to attack.

President Vladimir Putin, who has staked his political and personal prestige on the Games, has already ordered security measures beefed up nationwide since suicide bombers killed at least 34 people last month in Volgograd, also in southern Russia.

"Security forces have detained five members of a banned international terrorist organization," the NAC said in a statement received by Russian news agencies. An NAC spokesman confirmed the statement to Reuters.

"The anti-terrorism operation discovered and seized ammunition, grenades and a homemade explosive device packed with shrapnel ready for use," the statement said.

The Games open on Feb. 7 in Sochi, on the western edge of the Caucasus region, where insurgents want to carve out an Islamic state.

On Thursday, security forces went on combat alert in the southern Stavropol region after the discovery of at least five corpses with gunshot wounds and an explosive device.

The head of Russia's Olympic Committee has said Moscow has taken every possible measure to ensure the Games' safety.