(Specifies source in paragraph 2, adds new information, updates the number and types of aircraft involved in the drill in paragraphs 4, 5, 6)

MOSCOW, February 13 (RIA Novosti) - Russia's Air Force announced on Wednesday the launch of a tactical exercise involving long-range aviation in "northern latitudes" to rehearse interoperability in air patrol missions.

"The active phase of the tactical exercise has started under the command of long-range aviation commander Maj. Gen. Pavel Androsov," said Col. Alexander Drobyshevsky, an aide to the Air Force commander.

He did not say exactly where the exercise was being conducted or whether it was in Russia or outside its borders.

The drill, including two heavy-bomber regiments and one aerial tanker regiment, is practicing midair refueling, flights over uncharted terrain and in difficult weather conditions, as well as landings on off-base, alternate airfields.

Over 30 Tu-95 (Bear) strategic bombers, Il-78 (Midas) four-engine aerial refueling tankers, and Tu-22 (Blinder) supersonic bombers are participating in the exercise.

Drobyshevsky earlier said that more than 20 airplanes would participate in the drill.

Last August, Russia resumed long-range patrol missions of strategic bombers, which were suspended in 1992 following the breakup of the Soviet Union.

It said air patrol areas would include zones of commercial shipping and economic activity and would be conducted on a permanent basis.

NATO has requested that Russia give it advanced warning of military exercises.