The Russian Embassy in Kiev confirmed on Saturday 17 September that a group of 20 people attacked the Russian embassy with fireworks and a smoke pellet at around 1am. No one was hurt in the attack, said Kiev police, although the embassy building was damaged.

An investigation of the incident is taking place. "The information is being checked," the Russian Foreign Ministry told TASS on Saturday.

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A Kiev government spokesman said earlier that it cannot guarantee security of diplomatic missions during the elections.

Press secretary of the Russian president, Dmitry Peskov, said voting would be organised inside the diplomatic offices as Russian citizens are employed there, and the Ukrainian authorities cannot prohibit the polling.

The Ukrainian PM Volodymyr Groysman called the Saturday night attack on the Russian embassy in Kiev a small, though unacceptable incident.

"This is hooliganism, and this is unacceptable, because the Ukrainian capital Kiev must be a different kind of example of culture. That is why I think that such a small incident is not worth any comments," said Groysman, according to a report from Sputnik, Russian's state-controlled news agency.

On Sunday, the Russian Embassy is set to open polling stations for voting in elections to the State Duma of the Russian Federation. However, Ukrainian authorities have imposed a ban on holding elections in the country due to the ongoing conflict with Moscow over Crimea.

"Polling stations will be organised," Russian diplomats told Strana website. "About 80,000 citizens are on the lists of voters."

Attacks on the Russian embassy in Kiev are a frequent occurrence. The largest was in 2014, when the building was vandalised by a mob who overturned cars belonging to embassy staff and burned the Russian flag. TV footage shows Foreign Minister Andrey Deshchitsa standing in the crowd saying: "I would stand up here with you can say, Russia, get out of Ukraine," he said. "Putin's a f**ker, right!"

TV footage showed foreign minister Andrey Deshchitsa standing in the crowd saying: "I would stand up here with you can say, Russia, get out of Ukraine," he said. "Putin's a f**ker, right!"