ROSTOV-ON-DON, July 11 (RIA Novosti) - Four militants were killed in the Russian North Caucasus republic of Ingushetia on Saturday, a police source said.

"At about midday law enforcement bodies of Ingushetia and Chechnya engaged in a clash with a group of militants in Ingushetia's Sunzha District on the border with Chechnya. During the fight, law enforcement officers killed four members of illegal armed units," the source said.

The interior ministries of Chechnya and Ingushetia have been holding a joint operation to counter illegal armed units in the Sunzha District since mid-June.

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.