Ukrainian security forces surrounded thousands of ethnic Tatar protesters in the centre of the Crimean regional capital, Simferopol, on Tuesday, Russian Public TV reported.

"Since this morning the centre of Simferopol has been encircled by special purpose forces and troops of the national guard," the television's correspondent said.

"On the streets of the city we have seen not only armed servicemen but also mobile installations with large-calibre machine guns." Protesters numbering "thousands" have gathered outside the regional parliament to demand voting rights and special parliamentary representation for some 100,000 former Tatar deportees who have now returned to Crimea but have not been granted Ukrainian citizenship, the television said.

They request a meeting with the speaker of the Ukrainian parliament, Oleksandr Moroz, who is currently in Crimea.

The protesters threaten acts of civil disobedience including the blocking of the railway station and airport if their demands are not met.

"The leaders of the Crimean Tartars say that they fear provocations which in the very tense atmosphere could lead to clashes," the television said.

BBC Monitoring (http://www.monitor.bbc.co.uk), based in Caversham in southern England, selects and translates information from radio, television, press, news agencies and the Internet from 150 countries in more than 70 languages.