British Foreign Secretary William Hague in Ukraine de-escalation call
The Russian president has asked parliament to give permission for troops to be used in Ukraine to protect ethnic Russians and a military base in Crimea.
Mr Hague, who is travelling to Kiev for discussions tomorrow with interim leaders, has talked by telephone to his Russian counterpart Sergey Lavrov to call for calm as tensions heighten over the strategic region.
He tweeted: "Have spoken to Foreign Minister Lavrov to call for de-escalation in Crimea and respect for sovereignty and independence of #Ukraine."
Mr Hague has also spoken to German Foreign Minister Frank-Walter Steinmeier to discuss international diplomatic action to address the crisis.
Ukraine has accused Moscow of a "military invasion" after armed men yesterday seized control of airports in Crimea but the pro-Russian leader of the region today called on Moscow for support.
President Putin said Russia's military needed to be used "until the normalisation of the political situation in that country".