"Have spoken to Foreign Minister (Sergei) Lavrov to call for de-escalation in Crimea and respect for sovereignty and independence of Ukraine," Hague said in a Twitter message today.
The interim Ukrainian government accused Russia today of sending thousands of extra troops into Crimea in a bid to help local pro-Kremlin militia gain broader independence from the new pro-EU leaders in Kiev.
As the situation escalates, the Foreign Office confirmed Hague would visit Kiev tomorrow, although it did not give any further details.
Turchynov had yesterday appealed to Russian President Vladimir Putin to "stop military provocation" and withdraw from Crimea, after pro-Russian gunmen seized the government and parliament buildings in the capital Simferopol.
A little earlier, British Prime Minister David Cameron had called Putin to stress the importance of respecting Ukraine's territorial integrity.
US President Barack Obama has also said he is "deeply concerned" by reports of Russian troop movements in Ukraine, and warned there would be "costs" for any military intervention.