Ukraine's acting Defence Minister Igor Tenyukh Sunday dismissed Navy Commander Denis Berezovsky, who reportedly swore allegiance to pro-Russian Crimean authorities earlier in the day.
"The vacancy has been fulfilled by Rear Admiral Sergey Hayduk," Xinhua quoted the Ukrainian defence ministry as saying in a statement.
Information from Ukraine's Security Council said that the country's prosecutor's office launched a treason case against Denis Berezovsky, who was appointed as Ukraine's Navy chief a day earlier by Interim President Oleksandr Turchynov, for surrendering his headquarters in Sevastopol, a port in Crimea.
Crimean leader Sergey Aksyonov said Berezovsky would lead the Crimean Navy.
"The Rear Admiral (Berezovsky) has just taken the oath of allegiance to the people of the Crimea," the Interfax news agency quoted the Crimean authorities as saying.