GROZNY/ROSTOV-ON-DON, July 4 (RIA Novosti) - Nine policemen were killed and 10 wounded as a Chechen police motorcade fell into ambush in the Russian North Caucasus republic of Ingushetia on Saturday.

The two republics' interior ministries have been holding an operation against illegal armed units in Ingushetia's Sunzha district on the border with Chechnya since mid-June.

Fire on the motorcade that contained a UAZ off-road vehicle and four UAZ station wagons was opened on the road between the villages of Chemulga and Arshty at about 8:45 a.m. Moscow time [4:45 GMT].

The head of the Arshty administration was unhurt. Three vehicles were burned down. Police say the attack was planned beforehand.

"We are inclined to think that the motorcade got into a well-planned ambush. Fire on the vehicles was delivered from at least three points from assault rifles, machineguns and grenade launchers," an Ingush police spokesman said.

Chechen Interior Minister Ruslan Alkhanov vowed that the bandits will be brought to account. "Sooner or later we will find them. No crime remains unpunished," he said, adding that assistance will be given to the victims' families.

Russia's North Caucasus has seen an upsurge in violence of late, with the killing of Daghestan's Interior Minister Adilgerei Magomedtagirov and an assassination attempt on the Ingush President Yunus-bek Yevkurov this month.

The increase in violence has coincided with Moscow's decision to formally end its decade-long counterterrorism operation in Chechnya, which witnessed two brutal separatist wars in the 1990s and early 2000s.