NATO's top military commander has said Russia has amassed a force on Ukraine's eastern border large enough to pose a threat to other post-Soviet republics.

General Philip Breedlove, Supreme Allied Commander Europe, said the alliance was particularly concerned about the pro-Russian breakaway region of Transnistria in neighbouring Moldova.

"The (Russian) force that is at the Ukrainian border now to the east is very, very sizeable and very, very ready," Breedlove told an event held by the German Marshall Fund think-tank.

"There is absolutely sufficient (Russian) force postured on the eastern border of Ukraine to run to Transnistria if the decision was made to do that and that is very worrisome. Russia is acting much more like an adversary than a partner," he said.

Breedlove's comments followed an announcement by Russia that it had now taken control of 189 Ukrainian military installations in Crimea.

Russian troops on Saturday had used an armoured vehicle, automatic rifles and stun grenades to smash their way into bases at Belbek and Novofedorovka, which were among the last still under Ukrainian control after Moscow's armed takeover and subsequent annexation of Crimea. Ukrainian forces also abandoned a naval base after attacks by pro-Russian protesters.

Colonel Yuliy Mamchur, the commander of the base, said a Ukrainian serviceman had been injured and that he himself was being taken away by the Russians for talks at an unspecified location.

Asked if he thought he would return safely, Mamchur said: "That remains to be seen. For now we are placing all our weapons in the base's storage."

'Warship entered'

In a separate development, the Ukrainian warship Slavutych was raided by Russian troops in Sevastopol, Crimea residents told Al Jazeera, citing relatives of the crew.

Russians already boarded the ship at around 15:00 GMT, but Ukrainian crew members were refusing to leave the ship, locking themselves in cabins.

At about 1800GMT the crew was forced to leave the ship, a source told Al Jazeera.

A mother of one of the Ukrainian sailors told Al Jazeera that Russians have been trying to board the ship for 40 hours and when they did they started smashing up doors and windows.

Russian flag raised

One Ukrainian serviceman was killed and two others wounded since Russian forces started seizing control of military facilities in Crimea.

Ukraine's Defence Ministry said on Friday that Crimea's bases were still formally under Ukrainian control, but most were now occupied by Russian troops and flew Russia's tricolour flag.

Russian Defence Minister Sergei Shoigu ordered the Russian Black Sea Fleet commander to ensure Ukrainian servicemen who wanted to leave Crimea the possibility for organised moving to mainland Ukraine, the Russian defence ministry told Itar-Tass news agency.

According to the ministry, as of March 21, from more than 18,000 Ukrainian servicemen in Crimea, fewer than 2,000 had expressed the wish to leave for Ukraine.