An irate mob smashed the Russian embassy's windows in Kiev and threw a Molotov cocktail against its walls in the wake of the downing by pro-Kremlin rebels of a military plane that killed 49 troops.
Yesterday's violence came as top Russian and Ukrainian officials met for gas talks in Kiev but failed to make immediate progress, agreeing instead to resume negotiations today in a bid to avert an imminent cut in Russian supplies that would also affect large swathes of Europe.
The United States accused Russia of helping the insurgency by sending tanks and rocket launchers to the pro-Moscow rebels -- a charge the Kremlin denied.
A commander in the rebel-held eastern city of Lugansk, where the plane was shot down, showed pieces of the Il-76 transporter's charred debris in a wheat field a dozen kilometres (around eight miles) outside the airport.
The man known to his unit as Mudzhakhed (Sacred Fighter) said the plane tried to dump fuel after the rebels hit its engines. The heavy transporter crashed on its second landing approach after being hit by heavy machine gun fire.
He listed the mostly Russian-speaking region's grievances against the new more nationalist leaders in Kiev.
"They brought machine guns and ammunition," Mudzhakhed said. "We do not like people telling us what to do."
Ukraine's Western-backed President Petro Poroshenko vowed to deal the rebels "an adequate response" after the attack and signalled an imminent intensification of an offensive being waged against the insurgents. He proclaimed today a national day of mourning.
Poroshenko spoke moments before a crowd of several hundred smashed windows in the Russian embassy building and overturned several luxury cars belonging to its staff before pulling down its tricolour with the help of a wooden pole.
Later they threw a Molotov cocktail, which hit the wall of the building, but was quickly extinguished, according to an AFP reporter on the scene.
Russia condemned Kiev police inaction as "a grave violation of Ukraine's international obligations".
Washington also delivered Kiev a rare rebuke by urging "authorities to meet their Vienna Convention obligations to provide adequate security".
