As it happened: Ukraine crisis

Key Points

• Ukraine's acting President Oleksander Turchynov has accused Russia of deploying troops to Crimea and trying to provoke Kiev into "armed conflict"
• It comes amid unconfirmed reports that Russian planes have flown hundreds of troops into the region
• Armed men have blockaded airports in Crimea, Ukraine's only Russian-majority region and home to Russia's Black Sea Fleet
• Russia has denied involvement. President Vladimir Putin said sides had to stop "a further escalation of violence"
• US President Barack Obama warns Russia that "there will be costs for any military intervention in Ukraine" All times GMT
• At a news conference in Russia, Ukraine's ousted President Viktor Yanukovych says he is against any outside military intervention