SIMFEROPOL, March 20 -- Crimean law enforcement agencies on Thursday released Ukrainian navy commander Admiral Sergei Hayduk and seven other officers detained on Wednesday.

Local Kryminform news service said that the Ukrainian navy officers had been detained by the Crimean Sevastopol prosecutor's office for questioning.

Russian Defense Minister Sergei Shoigu reportedly appealed to the Crimean local authorities to let go the Ukrainian navy officers and to allow them to leave for Ukraine unhindered.

The detention occurred after Crimean self-defense units entered the Ukrainian navy commanding center on Wednesday and replaced Ukrainian flags with Russian flags.

No major clash happened when Ukrainian navy personnel vacated the center peacefully.

Crimean Prime Minister Sergey Aksenov said on March 14 that Ukrainian military personnel serving in Crimea would be given opportunities to choose either to leave or to stay.

Sergey Aksenov assured at a press briefing: "I' m absolutely sure that all military units will move to the March 17 side of the legitimate government or become the reserve.

"We guarantee payment of all monetary obligations that Ukraine had obliged to pay no matter what regions these departing military personnel were recruited from," Aksenov said.