All the the Ukrainian servicemen stationed in Crimea were allowed to leave for mainland Ukraine but 8,000 military men stayed and applied for permission to join the Russian army, Russian Defence Minister Sergei Shoigu said in televised comments on Friday.

Russia annexed the Black Sea peninsula in March after Crimea residents voted overwhelmingly to seek to join Russia. The referendum was called two weeks earlier, coinciding with the military occupation of the region by armed men in unmarked uniforms.

Shoigu on Friday described claims that the Russian army has mistreated Ukrainian servicemen as "improper and provocative." Several senior Ukrainian officers including a military base commander were briefly detained by the Russian forces and kept in custody for several days.

Moscow has never admitted that the thousands of troops roaming the peninsula, seizing the airports and putting up road blocks were in fact Russian. They wore no markings but some of them drove APCs with Russian number plates.

In what seems to be a cautious acknowledgement of the Russian military involvement in the peninsula, Shoigu said that Crimea faced "a threat to civilian lives and the threat of a seizure of the Russian military infrastructure by extremist organizations," so Russia "took decisive actions" and "beefed up security of Russian military infrastructure in Crimea."

He stopped short, however, of giving details but said the military "managed to prevent bloodshed."

Shoigu said Russia's actions did not violate any international laws because Russia never exceeded the agreed amount of troops stationed on the peninsula.

Ukraine and Western powers did not recognize the March vote and protested against the Russian annexation.