Russia is sending a "temporary detachment" of troops into the southern region of Dagestan to combat terrorism, the Interior Ministry said.
"We are talking about a temporary deployment and coordination to prevent and counter terrorism and extremism across the whole territory of Dagestan," Vyacheslav Makhmudov, a spokesman for the regional police, said from the republic's capital city, Makhachkala.
About 1,000 troops are being moved from the nearby region of Chechnya to form temporary police units in municipalities with "complicated criminal conditions," said Magomed Baachilov, the secretary of Dagestan's state security council.
The realignment of forces was ordered by Interior Minister Rashid Nurgaliyev, with Oleg Kizhayev, a police colonel, named in charge of the ministry detachment in Dagestan, police said.
The announcement came amid reports that authorities were deploying 20,000 to 25,000 federal troops from Khankala, the main Russian army base in Chechnya.
A convoy of armored personnel carriers and military vehicles was seen moving toward southern Dagestan from March 14 to March 17, according to reports published in Caucasian Knot, a Moscow-based news and analysis group, and the weekly Dagestani publication Chernovik, which cited unidentified local law enforcement officials.
The North Caucasus has been the scene of separatist violence since the collapse of the Soviet Union.
Federal forces fought two wars against rebels in Chechnya, and violence has been flaring in neighboring Dagestan, with a border shootout reported last month, a suicide bombing on March 6 and an attack on a local polling station during the March 4 presidential election.
The government blames continuing violence on Islamist fighters and insurgents.
Law enforcement agencies killed 171 militants and arrested 211 in Dagestan last year, with another eight surrendering without a fight, said Baachilov, of the region's state security council. One hundred "active members" of the insurgency remain after 15 were killed in the first two months of this year, he said.