MOSCOW, June 29 (RIA Novosti) - Four police officers have been injured in separate incidents in Russia's North Caucasus republics of Chechnya and Daghestan, police said on Monday.

Three police officers were wounded when an explosion occurred in the town of Gudermes, in western Chechnya, on Sunday. A police spokesman said the officers had been hospitalized, but did not offer further information.

In a separate incident in neighboring Daghestan, a police officer was badly injured in the south of the republic when unknown assailants opened fire on his car late on Sunday.

In another incident in Russia's Ingushetia, unknown militants launched an attack on the house of a police officer in Nazran, the republic's largest city, on Sunday night. No one was injured in the incident.

Russia's North Caucasus has seen an upsurge in violence of late, with Daghestan's Interior Minister Adilgerei Magomedtagirov killed and Ingush President Yunus-bek Yevkurov seriously injured in militant attacks this month.

The increase in violence 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.

Russian Security Council deputy head, Valentin Sobolev, claimed the rise in militant activity in the North Caucasus was linked to a rise in international terrorism.

"Above all, this is connected to the surge in international terrorist activity and the fact that militants have clearly received additional financial resources which allow them to do this," Sobolev said in an interview with RIA Novosti.