Ukraine crisis: UN's Ban Ki-moon urges de-escalation in Crimea

UN Secretary General Ban Ki-moon has expressed "grave concern" over developments in Ukraine.

In a statement, Mr Ban confirmed he had spoken to Russian President Vladimir Putin by telephone, and appealed to him to "urgently engage in direct dialogue with the authorities in Kiev".

US President Barack Obama also spoken to Mr Putin on Saturday, warning him that Russia has flouted international law by sending troops to Ukraine.