SEVASTOPOL (AFP) - Ukraine's acting president warned Crimea's Kremlin-backed leaders on Wednesday they had only three hours to release the captured head of the splintered ex-Soviet country's navy or face "an adequate response".
Pro-Russian forces had earlier seized two Crimean navy bases and detained Ukraine's naval chief as Moscow tightened its grip on the flashpoint peninsula despite Western warnings that its "annexation" would not go unpunished.
Dozens of despondent Ukrainian soldiers - one of them in tears - filed out of the Ukraine's main navy headquarters in the historic Black Sea port city of Sevastopol after it was stormed by hundreds of pro-Kremlin protesters and masked Russian troops.
The local prosecutor's office said Ukraine's navy commander Sergiy Gayduk - appointed after his predecessor switched allegiance in favour of Crimea's pro-Kremlin authorities at the start of the month - had been detained on suspicion of "ordering Ukrainian military units... to open fire on peaceful civilians".
Gayduk's capture delivered a huge blow to efforts by the new team of untested pro-Western leaders in Kiev to impose some authority in their crisis-hit country in the face of an increasingly assertive Kremlin.
Ukraine's acting president Oleksandr Turchynov scheduled an urgent security meeting and issued a statement around 6:00 pm giving the Crimean authorities until 9:00 pm (1900 GMT) to release the commander and other "hostages".
"Unless Admiral Gayduk and all the other hostages - both military and civilian ones - are released, the authorities will carry out an adequate response... of a technical and technological nature." Defence ministry officials earlier said that Russian forces had seized a second military base in Crimea's western port town of Novoozerne after using a tractor to ram open its main gate.
The Ukrainian government's loss of control of the heavily Russified region was underscored further when acting defence minister Igor Tenyukh was forced to cancel a visit aimed launching Crimean mediation talks when the local authorities threatened to turn back his plane.