Russian forces assumed control of the Ukrainian Navy HQ in the Crimean town of Sevastopol yesterday after demonstrators stormed the premises early in the morning.

Several thousand people gathered outside the HQ before cutting fences, storming inside and changing the flags on the flagpoles.

Some participants sang the Russian national anthem. They carried Russian and St Andrew's flags, the latter being the Russian naval ensign.

Ukrainian servicemen lined up to face the incoming throng, but they were helpless in light of superior numbers, obliging Ukrainian Navy Rear Admiral Sergey Haiduk to lead 30 members of his force from the base.

The Ukrainian Defence Ministry in Kiev announced that its armed forces commander Mikhail Kucin had informed Russian counterpart Valery Gerasimov that he has authorised use of military force by troops stationed in Crimea.

This was in response to the previous evening's conflict which claimed the lives of one Ukrainian soldier and another from the Crimean self-defence force.

The coup-installed government in Kiev revealed that its defence minister and deputy prime minister had planned to travel to Crimea yesterday, purportedly to avert an escalation in hostilities.

However, Crimean Prime Minister Sergei Aksyonov said: "They are not welcome in Crimea. They will not be allowed to enter Crimea. They will be sent back."

Kiev government Welfare Minister Lyudmila Denisova confirmed later that the pair had been denied entry to Crimea. She said that an emergency session of the National Security and Defence Council would be held in response.

Russia's Constitutional Court chairman Valery Zorkin confirmed yesterday that the treaty signed by President Vladimir Putin with Crimean officials has been ruled valid, thus formally clearing another hurdle for Moscow to annex Crimea.

The treaty now only requires ratification by the Russian parliament.