Donetsk, one of the last bastions of pro-Russian rebels in eastern Ukraine, has become a ghost town as residents clog the roads and railway stations in a desperate scramble to escape advancing government troops.

The self-proclaimed prime minister of the Donetsk People's Republic, Oleksandr Borodai, claims more than 70,000 of the city's 900,000 inhabitants have already fled as Kiev's forces move within 20 kilometers (12 miles) of the city.

The Canadian government of Prime Minister Stephen Harper has added 14 individuals to a list of people facing economic sanctions and travel bans related to the Ukranian crisis.

"Russia's illegal occupation of the Crimean peninsula and provocative military activity remains a serious concern to Canada and the international community," Harper said in a statement Friday.

Panicked Ukrainians flooded highways and packed trains leading out of the main remaining rebel stronghold on Saturday fearing a reprisal assault by government forces after they lost 30 servicemen to defiant militants.

Separatists near the Russian border mowed down 19 troops in a hail of heavy rocket fire on Friday in a bloody reminder of their resolve to reverse the recent tide of government gains across the eastern rustbelt.

Russia has circulated a proposal for a United Nations Security Council resolution on Ukraine that would demand a ceasefire between Kiev and pro-Russian insurgents, Moscow's ambassador said Friday.

Other elements of the measure would give a greater role to the Organization for Security and Cooperation in Europe, Vitaly Churkin told reporters.

The European Union on Friday slapped a travel ban and asset freeze on 11 people allegedly linked to separatist violence in eastern Ukraine.

The decision brings the total number of people on an EU sanctions blacklist to 72, with two firms in Crimea also subject to an asset freeze, an EU statement said.

Ukraine has vowed to make pro-Russian rebels pay after losing 23 servicemen in clashes across the separatist east, while Russia proposed a U.N. resolution demanding a ceasefire to Europe's deadliest conflict in decades.

The Ukrainian defense ministry said Friday the death toll included 19 troops killed in a hail of rockets fired from a truck-mounted Grad rocket launcher system -- a type of weapon both Kiev and Washington insist could only have been covertly supplied to the rebels by Russia.

A new Amnesty International report on Friday highlighted the "hundreds" of abductions and incidents of torture by pro-Russian separatists in Ukraine, and also criticized the excessive force used by government forces.

"They beat me with their fists, a chair, anything they could find. They stubbed out cigarettes on my leg and electrocuted me. It went on for so long, I couldn’t feel anything anymore. I just passed out," Sasha, a 19-year-old kidnapped in the eastern city of Lugansk, told the rights group in the report.

Among a sea of sunflowers, shirtless Ukranian soldiers shout advice to an earthmover's driver who digs, in a thick cloud of fumes, trenches around their armored vehicles, on which they are perched in an open field.

The column had arrived unchallenged from the city of Mariupol, in Ukraine's southeast, on Wednesday evening.

Russian President Vladimir Putin looks set to meet German Chancellor Angela Merkel amid tensions over Ukraine when both leaders attend the World Cup final in Rio de Janeiro, the Kremlin said Thursday.

Presidential adviser Yury Ushakov said the meeting had not been finalized but Putin was due to have a series of bilateral encounters with world leaders at the match on Sunday and that a tete-a-tete with Merkel appeared to be on the cards. 

Ukraine warned on Thursday that its assault on pro-Russian insurgents may last another month and rejected calls for a ceasefire as it moved tanks within striking distance of the rebels' two remaining strongholds.

An AFP team about 20 kilometers (12 miles) south of the eastern hub of Donetsk -- to which most of the militias have retreated -- saw heavy armored vehicles fan out across the rolling corn and sunflower fields of the economically-vital rustbelt.