Minsk's defence ministry said "joint tactical flight drills of aviation units" from Belarus and Russia had started.

The drills will last until February 1, the ministry said earlier.

"The main goal of the exercise is to increase operational compatibility in the joint performance of combat training missions," the ministry said in a statement.

All military airfields in Belarus will be involved in the drills, Minsk has said.

The ministry added that the exercises will involve training in aerial reconnaissance, joint patrolling of the state border, tactical air assault landing, the delivery of goods and evacuation of wounded.

Officials have described the drills as defensive.

"The exercise is purely defensive in nature," Pavel Muraveyko, first deputy state secretary of Belarus's Security Council, said in remarks carried Sunday by the defence ministry's Telegram channel.

He added that the situation on Belarus's border with Ukraine was "not very calm" but Minsk is ready for "any provocative actions" from Kyiv.

President Alexander Lukashenko has insisted that he will not send Belarusian troops into Ukraine.

Belarus allowed Russia -- its main political ally and chief creditor -- to use Belarusian territory as a launching pad for its Ukraine offensive.

In October, Minsk said it was establishing a joint regional force with Moscow with several thousand Russian servicemen arriving to the country.