Kiev protest
Protesters gather near the Russian embassy in Kiev June Reuters

The political dispute between Ukraine and Russia has taken an unusual turn after Ukraine's Foreign Minister was heard to call Russian President Vladimir Putin a "dickhead".

Addressing anti-Moscow protesters outside the Russian embassy in Kiev on Sunday, acting Foreign Minister Andriy Deshchytsia urged the crowd to refrain from attacking the building.

"We must fulfil our international obligations, including defending the right of Russia to have an embassy in Ukraine," he told hundreds of young demonstrators.

After he was challenged by the crowd, Deshchytsia said he backed the protesters' demands.

"Did I say that I am against you protesting? I am for you protesting. I am ready to be here with you and say 'Russia, get out of Ukraine'."

"Yes, Putin is a dickhead," he added, resulting in the crowd chanting the phrase back at him.

"Putin khuilo" has become a popular rallying cry among Ukrainians opposed to Russia's interventions in the east of the country. Khuilo is a Russian obscenity that roughly translates as "dickhead" or "fucker".

Hundreds of demonstrators assembled at the Russian embassy in Kiev on Saturday to protest after pro-Russian militants shot down a plane in the eastern city of Luhansk, killing all 49 military servicemen on board.

It is the biggest loss of life in a single incident since Kiev launched an "anti-terror" operation in the east of the country, where separatist militias have declared republics independent of Kiev. Sunday was declared a national day of mourning in Ukraine.

The crowd hurled eggs and paint at the building and covered the gate in swastikas, before overturning cars.

Russia reacted furiously to the events, blaming the "inaction" of the Kiev police for the damage caused.

The Kremlin has called on Ukraine's president to sack Deshchytsia.

"I can't really imagine how anyone, especially a Russian representative, can sit down at the negotiating table with him after such an outburst," Foreign policy official Leonid Kalashnikov told a Russian radio station.

Deshchytsia told Ekho Moskvy that he had urged the demonstrators to remain peaceful. When asked about the Putin remarks, he was reluctant to expand. "I have told you what I want to say. You asked for my comments (on the rally), I've made my comments."