ROSTOV-ON-DON, July 5 (RIA Novosti) - Police in Russia's North Caucasus Republic of Ingushetia have blocked up to 20 militants believed to be behind Saturday's attack that killed nine and wounded ten Chechen police, the republican security council said on Sunday.

"About 22 hours [18:00 GMT] on Saturday, police of the Ingush and Chechen interior ministries blocked up to 20 militants in the village of Datykh during a special operation. Artillery and mortar fire was opened on them at night and search measures were launched in that area on Sunday morning," said Alexei Vorobyov, secretary of the Ingush Security Council.

A motorcade of Chechen police was ambushed in Ingushetia's Sunzha district bordering on the Chechen Republic during a special operation of the Chechen and Ingush interior ministries against illegal armed formations.

Chechen President Ramzan Kadyrov on Saturday vowed tough measures against the assailants, saying they would be held responsible for the attack.

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 last 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.