Moscow announced on Thursday it would hold field training for tank, artillery and infantry units in three regions next to the Ukrainian border.

Moscow announced on Thursday it would hold field training for tank, artillery and infantry units in three regions next to the Ukrainian border.

The move came as thousands of paratroopers also began exercises close to Ukraine on Thursday, ahead of a referendum in Crimea on it joining Russia on Sunday.

The armed forces are "increasing the intensity of field training exercises," the defense ministry said in a statement, saying the exercises were being carried out in the Rostov, Belgorod and Kursk regions bordering Ukraine, as well as one non-border region.

"The main aim .. is a multi-faceted check of the units' cohesiveness followed by the performance of battle training assignments in unfamiliar terrain and untested firing ranges," the ministry said.

It said the exercises would continue until the end of March but did not specify how many troops were involved.

In a separate drill, 4,000 paratroopers launched exercises in the Rostov region on Thursday set to continue until March 14, the ITAR-TASS news agency cited the defense ministry as saying. Russian state television showed hundreds of parachutes floating down to land.

Deputy Defense Minister Anatoly Antonov said Wednesday Moscow had permitted a request for a Ukrainian reconnaissance plane to carry out an observation flight over the border regions.