Russia has announced it is to conduct new military exercises near the border of Ukraine in a show of strength, as tensions between the two continue to rise.

Russian air force spokesman Igor Klimov, told Interfax news agency that more than 100 aircraft, including Su-34 bombers and MiG-31 fighters, would conduct missile practice during the drills.

Klimov said that the exercises were taking place to improve the unity of the air force, and he did not mention Ukraine in his statement.

The exercises are set to take place from Monday to Thursday. Russia's defence ministry was not available for comment.

The move by Russia comes as the Ukrainian army moves in on the eastern separatist strongholds of Donetsk and Luhansk.

Fighting between Ukrainian forces and pro-Russian rebels has continued, as Kiev seeks to win back control of Donetsk, the country's fifth biggest city.

Luhansk's civilians are also preparing for a government offensive, stockpiling on food and sleeping in basements, as the city is surrounding by government forces and now without power, according to the BBC.

In light of the recent MH17 crash which killed all 298 passengers, Western governments have condemned Russia for supplying arms to the separatists who are feared to have downed the aircraft.

The separatists declared independence from Kiev in referenda held in the Donetsk and Luhansk regions earlier this year. Both referenda were later declared illegal by the European Union and the United States.