Russia said Monday it would dispatch a humanitarian convoy to conflict-torn east Ukraine despite fierce warnings from the West that Moscow not act alone as a cover for sending in troops.
A Ukrainian soldier stands guard at a check-point near the eastern city of Donetsk on August 11, 2014
Russia insisted its military would not be involved in the convoy, but Kiev said Moscow could only play a role as part of a broader Red Cross mission.
Russian President Vladimir Putin told European Commission chief Jose Manuel Barroso that Moscow "is sending a humanitarian convoy to Ukraine in cooperation with representatives of the International Committee of the Red Cross."
In a telephone call with Barroso, Putin slammed the "catastrophic consequences of the military operation led by Kiev authorities" in eastern Ukraine and stressed the need for an immediate humanitarian mission, the Kremlin said in a statement.
Barroso in turn "warned against any unilateral military actions in Ukraine, under any pretext, including humanitarian," Brussels said in a statement.
NATO says the Kremlin has massed 20,000 troops at the Ukrainian border and there is deep concern in the West that Russia will intervene to protect pro-Moscow separatists under threat from a government onslaught.
Putin's spokesman Dmitry Peskov insisted the military would not be involved in Russia's convoy.
- No 'military escort' -
"There won't be a military escort," Peskov told AFP, adding that the mission has been "agreed with Kiev".
He said he could provide no further details about the convoy or a timetable for the mission.
Local authorities in insurgent-held cities in eastern Ukraine -- where more than 1,300 people have been killed and 285,000 forced from their homes in recent months -- have warned of a humanitarian catastrophe as water, power and food supplies are cut.
Ukraine said it was willing to accept help, but from a broader mission involving Western nations.
Kiev said President Petro Poroshenko had spoken by telephone to US President Barack Obama about a possible Red Cross mission that would also involve the US, European Union and Germany helping to deliver aid to the stricken city of Lugansk.
"Barack Obama confirmed the intention of the USA to take active part in the international humanitarian mission," Kiev said in a statement.
The White House said the two leaders had agreed during the call "that any Russian intervention in Ukraine without the formal, express consent and authorisation of the Ukraine government would be unacceptable and a violation of international law."
The White House said Poroshenko had updated Obama on efforts with the Red Cross for a "multilateral" aid mission but it made no direct mention of US participation.
Over the weekend, Obama, German Chancellor Angela Merkel and British Prime Minister David Cameron warned that any unilateral move by Russia into Ukraine would be considered "illegal" and "unacceptable".
Ukraine's military say they are close to completely surrounding rebel forces hunkered down in the key bastions of Donetsk and Lugansk.
The fighting has left residents in the rebel-held cities without basic necessities, prompting local authorities to warn of an impending humanitarian disaster.
- 'Edge of survival' -
Lugansk, the rebels' second-largest base, was teetering "on the edge of survival", with no power and running water for more than a week, and fuel, food and medicines also short, city authorities said.
International observers have also reported dire conditions in Donetsk and Shakhtarsk in recent days.
As fighting continued over the past 24 hours, six soldiers were killed and 24 injured, bringing Kiev's death toll to 568 troops in four months, Ukraine's military said Monday.
Shells again rained down on inner city areas of the main separatist bastion of Donetsk.
A high-security prison in a western district of the million-strong city was struck by mortar fire late Sunday, killing one inmate and injuring five, and allowing 106 to escape, prison authorities said.
Two prison officials were also wounded, the authorities said, adding that by Monday morning 34 of the inmates had been returned to the prison.
The mining hub, once known for its leafy streets, has been pummelled by heavy fire for days, leaving a growing number of civilian casualties as homes and hospitals have been hit.