The Ukrainian parliament approved the formation of a national coalition government earlier today.
In this image, Ukraine's new prime minister Arseny Yatseniuk poses with the rest of his cabinet for the first time since their appointment by parliament.
Nato's Secretary General Anders Fogh Rasmussen says he is "extremely concerned" after gunmen stormed government buildings in Crimea. The group raised a Russian flag and with it raised fears of a regional conflict.
Armed men seized the parliament in Ukraine's Crimea region on Thursday and raised the Russian flag, alarming Kiev's new rulers, who urged Moscow not move troops out of its navy base on the peninsula.
The latest challenges to attempts to set up a new national government in the capital Kiev were discussed by Mr Cameron and German chancellor Angela Merkel at talks in 10 Downing Street.
Ms Merkel said: 'We will do everything we can in order to support this government that has a tremendously difficult economic situation".
"The issue of the territorial integrity of Ukraine is of central importance to us".
Ukraine has requested support from the International Monetary Fund, its Managing Director Christine Lagarde has confirmed.
Lagarde said the IMF is discussing with international partners how best to help Ukraine, and will send a team to Kiev in the coming days.
Ukrainian finance minister Oleksander Shlapak said they are asking for at least $15 billion.
"Today we requested the IMF send a mission and we hope that it will be here next week," the minister was quoted as saying by Interfax news agency.
2,000 pro-Russian protesters are demonstrating outside Ukrainian government buildings on the country's Crimea peninsula.
ITV News Europe Editor James Mates and ITV News cameraman Mark Nelson have tweeted photos of the protest, which follows the seizing of a regional government building by armed men.
Demonstrators outside the parliament building in Simferopol. http://t.co/jGfqBGtXLE
The US has warned Russia over their military exercises along the border with Ukraine, saying they should not take any steps that could be misinterpreted or "lead to miscalculation".
"I'm closely watching Russia's military exercises along the Ukrainian border," U.S. defence secretary Chuck Hagel said at a NATO news conference.
"I expect Russia to be transparent about these activities, and I urge them not to take any steps that could be misinterpreted, or lead to miscalculation during a very delicate time - a time of great tension."
Ukraine's new prime minister Arseny Yatseniuk has accused the former government of stripping state coffers bare, saying $37 billion of credit it had received had "disappeared".
Speaking in parliament , Yatseniuk said that in the past three years "the sum of 70 billion dollars was paid out of Ukraine's financial system into off-shore accounts".
"I want to report to you - the state treasury has been robbed and is empty," he said. "37 billion dollars of credit received have disappeared in an unknown direction," he added.
Ousted President Viktor Yanukovich has not been seen since Saturday, but Russian news agencies have reported that Russia has agreed to provide him with protection.
The Ukrainian parliament has approved the formation of a national coalition government.
The parliament has proposed former economy minister Arseny Yatseniuk to lead the coalition as prime minister.
"Our country is on the brink of economic and political collapse," Yatseniuk told parliament after his nomination.
He warned that Ukraine faced threats to its territorial integrity, and promised to pursue European integration.
But he also warned of "unpopular" decisions ahead to tackle the crisis.
The new government follows the overthrow of President Viktor Yanukovich, who has not been confirmed as having been seen since Saturday.
Russian president Vladimir Putin has ordered military exercises for 150,000 troops.
It comes after Russian flags were raised from government buildings on Ukraine's Crimea peninsula, which armed men have seized.
The exercises follow the Russian foreign ministry's pledge to "strongly and uncompromisingly" react to any violation of the rights of Russian compatriots in Ukraine.
They are among the largest such exercises Russia has undertaken in recent years.