UK & World News
US Accuses 'Lying' Russia Of Ukraine Incursion
The United States has accused Russia of sending combat forces across the border into Ukraine as it warned Moscow economic sanctions may be tightened.
Speaking at the White House, President Barack Obama said Russia has been supporting pro-Moscow separatists in eastern Ukraine "for months".
He ruled out any direct US military intervention but said Russia - which has repeatedly denied any involvement in Ukraine - would incur "more costs and consequences".
"I consider the actions that we've seen in the last week a continuation of what's been taking place for months now," Mr Obama said.
"The separatists are backed, trained, armed, financed by Russia. Russia determined that it had to be a little more overt in what it had already been doing, but it's not really a shift."
Ukraine said on Friday Russia's call for separatists to open a 'humanitarian corridor' to allow encircled Ukrainian troops to withdraw clearly showed they were "led and controlled directly from the Kremlin".
Meanwhile, Washington's envoy to the United Nations hit out at Russia during an emergency session of its Security Council
US Ambassador Samantha Power said: "Russia has to stop lying and has to stop fueling this conflict.
"The mask is coming off. We see Russia's actions for what they are: a deliberate effort to support and now fight alongside illegal separatists in another sovereign country."
State Department spokeswoman Jen Psaki said Russia has stepped up its military presence in the east.
She said Russia has sent "combat forces, armoured vehicles, artillery, and surface-to-air systems" to Ukraine.
Ms Psaki also accused Russia of "playing a direct supporting role to the separatists' proxies and mercenaries".
According to the UN, a total of 2,593 people have been killed in the fighting in eastern Ukraine since it erupted in mid-April.
It said the figure includes civilians as well as Ukrainian and separatist combatants, but not the 298 victims of the MH17 Malaysian Airlines plane crash.
"The trend is clear and alarming. There is a significant increase in the death toll in the east," Ivan Simonovic, UN Assistant Secretary General for Human Rights, told journalists.
He predicted civilian casualties would continue to rise "as each side increases its strength, through mobilisation, better organisation or the deployment of new fighters and more sophisticated weapons and support from outside
Nato is due to hold an emergency meeting on the crisis later today, while German Chancellor Angela Merkel said an EU summit on Saturday would discuss the prospect of further sanctions.
A spokesman for Ukraine's National Security Council, Colonel Andriy Lysenko, said earlier two columns of tanks had fired at a border post, before rolling into Ukraine.
His comments followed Ukrainian President Petro Poroshenko's claim on Thursday that Russian forces had "entered" the country.
The tanks are reported to have crossed into a southern area of the Donetsk region, where the separatists have made significant gains in recent days.
A Nato official said at least 1,000 Russian troops had crossed into Ukraine with sophisticated equipment and had been in "direct contact" with Ukrainian forces, resulting in casualties.
At a crisis meeting of the UN Security Council, Russian Ambassador Vitaly Churkin accused Kiev of "waging war against its own people."
However, Britain's Ambassador to the UN, Mark Lyall Grant, said there was "overwhelming" evidence to the contrary.
"It is simply not credible for Russia and its proxies in (the eastern regions of) Donetsk and Luhansk to keep claiming that these serving members of the Russian armed forces are in Ukraine by accident or on holiday," he said.