Armed men wielding assault rifles took up fresh positions outside military installations in Crimea Monday as authorities said all of Ukraine's bases in the flashpoint peninsula were surrounded by pro-Russian forces.
Kiev said Russian troops were continuing to pour into Crimea and a regional defence ministry spokesman told AFP that armed men had surrounded all of its facilities.
But the spokesman, Vladislav Seleznev, insisted that Ukraine was still in control of all of its bases after defiant troops refused to hand over control.
"All of the bases in Crimea are still under Ukrainian control but are surrounded," he said, adding that despite the tensions so far no violence had erupted.
"There have been no shots fired, except for one warning shot in the air yesterday at Belbek (near Sevastopol) by the Ukrainians," Seleznev said.
AFP reporters in various parts of the peninsula saw armed men believed to be Russian soldiers taking up or cementing positions outside Ukrainian military installations.
The Ukrainian defence ministry says some 6,000 Russian troops have been sent by the Kremlin to Crimea -- a Russian-speaking autonomous region that has been thrown into disarray since the ouster of Moscow-backed president Viktor Yanukovych last month.
Armed men believed to be under Moscow's orders last week seized key government buildings in Crimea and airports on the peninsula.
Regional lawmakers deposed the Kiev-appointed prime minister and have called for a referendum on March 30 on proclaiming greater autonomy for Crimea.
AFP reporters said Monday that armed men had surrounded the Ukrainian military base in Bakhchisaray, about 30 kilometres (20 miles) southwest of the Crimean regional capital Simferopol.
About 20 soldiers were visible around the small base, which Ukrainian media said contained a Navy provisions centre.
Its commander, Sergey Stechenko, told reporters outside the base that the armed men had ordered them to surrender the facility and its store of weapons.
"We cannot do this, we have sworn an oath to Ukraine," he said, refusing to provide details about the base or the number of soldiers inside.
"They don't want to shoot at us, we don't want to shoot at them," he said, "but if they start shooting, we will fire back."
AFP reporters said hundreds of armed men also remained in a tense standoff with Ukrainian soldiers at Perevalne, which hosts the 36th Coast Guard Brigade about 30 kilometres southeast of Simferopol.
The armed men had approached the base early on Sunday and demanded its surrender but the Ukrainian soldiers inside refused.
As with other standoffs, the situation was tense but peaceful and some local residents were gathering outside the base to voice their backing for Moscow.
"I came here to support the Russian army," said Oleg, a local resident in his 50s wearing a ribbon in the colours of the Russian flag.
"It's up to us to decide who we want to live with -- with Russia, alone or with Ukraine, whose government we don't recognise."
In Sevastopol, a bastion of pro-Kremlin sentiment, AFP reporters said a handful of unidentified armed men in camouflage and a crowd of local pro-Russian residents were blocking an entrance to headquarters of the Ukrainian naval forces in Crimea.
In a dramatic turnaround on Sunday, Ukraine's navy chief Denis Berezovsky switched allegiance to the pro-Russian authorities of Crimea, fuelling fears that the peninsula is sliding out of Kiev's grasp.
Ukrainian sailors could be seen peering through the gate at the headquarters. A truck trying to deliver food was prevented from entering.
"We want to get rid of these foreign -- Ukrainian -- troops," said Alexander Dukhanin, a member of a local "self defence" group.
"We want them to go... We have offered them the choice to join our Crimean forces or leave."