Dozens killed in blaze at pro-Russia base in Odessa

A pro-Russian activist aims a pistol at supporters of the Kiev government during clashes in the streets of Odessa.

The violence in Ukraine spread to the southern City of Odessa today fueling fears that the country is spiralling towards all-out civil conflict.

More: Ukraine troops confronted by angry Slaviansk residents

Thirty-one pro-Russian separatists were reportedly killed in a fire during clashes between rival groups in the southern port city. At least three Ukraine service men have been killed in skirmishes in Sloviansk.

Two Ukranian Army helicopters were also shot down in the east of the country as the government launched an offensive against rebels.

The flash on this picture is believed to be a missile impact on a Ukrainian helicopter Credit: ITV News

ITV News Europe Editor James Mates reports from Ukraine

Officials in Kiev are claiming that Moscow is preparing an invasion force tens of thousands strong on the frontier with Ukraine and that "Russian sabotuers" are sowing the seeds of unrest in the east to ease the way.

The Kremlin has deined these allegations, but the Russian foreign minister Sergei Lavrov has warned that his country would respond to attacks on their citizens or interests in Ukraine. Vladmir Putin's spokesman said that the Ukrainian offensive had "effectively destroyed the last hope for the implementation of the Geneva agreement."

More: Geneva talks: Key points on Ukraine crisis

A protester throws a petrol bomb at the trade union building in Odessa. Credit: Reuters\Yevgeny Volokin

Unlike the rest of the country, the port city of Odessa in the south had been largely untouched by violence until today but clashes today between pro-Russian separatists and activists loyal to the government in Kiev left at least 38 dead, according to local police and security forces

More: Flames surround 'pro-Russian base' in Odessa

People wait to be rescued on upper storeys at the trade union building in Odessa. Credit: Reuters\Yevgeny Volokin

At Russia's insistence, the United Nations Security Council held an emergency session on Ukraine but again failed to agree action.

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