Fierce fighting between government forces and pro-Russian rebels has killed 34 civilians over the past 24 hours in east Ukraine's Donetsk region, local authorities have said.

"Over the past day as a result of military hostilities, 34 residents of the region died and another 29 were wounded," the regional administration said in a statement.

Meanwhile, the Russian defence ministry said this morning it was conducting fresh military exercises in southern Russia.

The major test of long-range anti-aircraft and anti-missile systems will take place at the Ashuluk base in the southern Astrakhan region, several hundred kilometres from the fighting in eastern Ukraine, a spokesman told Interfax news agency.

"Today there will be around 20 launches of S-300 and S-400 rockets. The surface-to-air missile systems should provide a massive strike on the hypothetical enemy, destroying high-altitude, low-altitude and ballistic targets," the agency quoted Colonel Igor Klimov as saying.

He said the exercise would simulate a possible air and missile attack, and involve more than 800 soldiers and 200 pieces of military equipment.

The surface-to-air missile systems used in the training are different from the medium-range Buk system believed to have been used by pro-Russian separatists to shoot down Malaysia Airlines Flight MH17 over eastern Ukraine on 17 July, killing all 298 on board.

The West believes the Buk system was supplied by Russia, although Russia denies this and has blamed Ukraine for the tragedy.

Russia has conducted numerous military exercises this summer which the West has criticised as intending to intimidate Ukraine.