The Belarusian defence ministry said it was hosting the combat readiness drills because of the continuing "aggravation" of tensions "including at the western and southern borders of the Republic of Belarus."

Russia -- a close ally of ex-Soviet Belarus -- and the West are engaged in intensive diplomacy after Moscow sent tens of thousands of troops to its borders with Ukraine in preparation for what Kyiv and its Western allies say is a possible invasion.

Neither Russia nor Belarus have said how many troops would be involved in the drills, which Belarus said Tuesday would take place in two stages.

The defence ministry said the first part of the excercise would continue from Tuesday until February 9 and focus on speedy troop deployments, securing government and military facilities, as well as joint airforce firing drills.

The second stage will take place between February 10 and 20 and centre on efforts to strengthen border defences, the ministry said.

Belarusian strongman Alexander Lukashenko announced earlier this week that Russian and Belarusian troops would hold the exercises, citing what he said was the growing foreign military presence in Ukraine and NATO member Poland.

Western capitals accuse Moscow of sending around 100,000 soldiers to regions surrounding Ukraine, which also borders Belarus, in preparation for a possible assault.