Russian President Vladimir Putin has ordered his defence minister to pull thousands of troops from the border with Ukraine, the Kremlin said ahead of key talks on a fragile truce in the ex-Soviet country.

"The head of state has tasked the defence minister with beginning to bring troops back to their permanent bases," the Kremlin said late Saturday evening.

The Kremlin said the order meant that 17,600 servicemen, who had in the summer participated in military drills in the southern Rostov region on the border with Ukraine, would be pulled back.

Defence minister Sergei Shoigu received the order after reporting that "summertime training on military ranges of the Southern military district is over," the Kremlin said.

The late Saturday meeting between Putin and his defence minister took place after the president chaired a meeting of his national security council, said the Kremlin, without providing further details.

Putin is expected to meet Ukrainian President Petro Poroshenko for key talks on the sidelines of a Asia-Europe forum in Milan on Friday.

Kiev reported that pro-Moscow rebel attacks had subsided and Poroshenko said for his part the two would discuss the fragile truce agreed last month.