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

The announcement by the Kremlin late Saturday comes as the Russian strongman is gearing up to hold the talks with Ukrainian President Petro Poroshenko and European leaders in Milan on Friday, signaling the possibility of shoring up the rickety truce.

Australian Treasurer Joe Hockey confirmed Sunday Vladimir Putin will attend the G20 leaders' summit in November, despite concerns about Russia's actions in Ukraine in recent months.

Australia's confirmation that the Russian leader would attend the high-powered summit came after Ukraine's President Petro Poroshenko said he would also meet Putin next week.

Fugitive U.S. intelligence analyst Edward Snowden, who was granted asylum by Moscow after revealing the extent of U.S. government surveillance, has been joined by his American girlfriend in Russia, a documentary reveals.

The nearly two-hour film "Citizenfour" by Laura Poitras paints an intimate portrait of Snowden holed up in a Hong Kong hotel as he blows the whistle on National Security Agency dealings and then plots his escape.

A new U.N. Syria envoy is expected to arrive for talks in Russia on October 21, the foreign ministry in Moscow said on Saturday.

Staffan de Mistura "will meet with Russian foreign minister Sergei Lavrov", deputy foreign minister Gennady Gatilov told the Interfax news agency.

Ukraine's President Petro Poroshenko on Saturday said he will meet with Russia's Vladimir Putin next week as Kiev reported rebel attacks have subsided, signaling the possibility of rescuing a truce in the six-month conflict.

Pro-Russian rebels and the Ukrainian military in the eastern Donetsk region said they have agreed to a no-shooting period, and the army announced "progress" in negotiations and readiness to pull back forces.

Russia's justice ministry has filed a case to disband leading human rights group Memorial, the organisation's president told AFP on Friday.

The Supreme Court in Moscow said in a statement it will hear the case on Monday but gave no other details on its website.

A Russian court on Friday extended the house arrest of opposition leader Alexei Navalny, who faces graft charges his supporters say are politically motivated. 

"The house arrest has been prolonged until January 14," Navalny's lawyer Vadim Kobzev told Agence France-Presse.

Three Ukrainian civilians died overnight in mortar fire around Donetsk airport, where government forces held out against pro-Russian rebels in the latest deadly violation of a ceasefire, officials said Friday.

The Donetsk mayor's office said the clashes, in which five people were wounded, lasted nine hours.

A Russian national arrested this year by U.S. officials was indicted on additional hacking charges, alleging he led a scheme to steal some two million credit card numbers, officials said.

Roman Valerevich Seleznev, the 30-year-old son of a Russian lawmaker, now faces 40 criminal counts including wire fraud and identity theft, the Justice Department said in a statement Thursday.

Former Soviet leader Mikhail Gorbachev was on Friday discharged from a Moscow clinic where he had been admitted for medical tests.

"I am feeling better today than I was yesterday. That is why doctors agreed that it was possible to allow me to leave the clinic," Gorbachev, 83, told the Interfax news agency.