By Ellie Tzortzi
BELGRADE, May 19 (Reuters) - Montenegro votes in an independence referendum on Sunday which could dissolve its union with Serbia and allow the tiny Balkan state to seek membership of the wealthy European Union on its own.
The choice has more to do with Montenegrins' feelings for Serbia than for the abstract union established three years ago in which Serbia is the dominant partner.
The two Balkan neighbours have been together for almost a century -- in two kingdoms, in Josip Broz Tito's socialist Yugoslavia and in the rump Yugoslav federation of late Serbian leader Slobodan Milosevic.
But Montenegro's pro-independence government says ending the union will bring economic development and a faster path to the EU, which this month froze talks on closer ties over Belgrade's failure to arrest war crimes fugitive Ratko Mladic.
The pro-union camp says Montenegro is too small to survive alone and cannot afford to lose out on the jobs, education and health care their far more populous neighbour has to offer.
But in the Balkans, where politics constantly refers back to old battles, long-dead kings and treason plots, it is emotional arguments about identity and belonging that sway voters most.
Serbia is the dominant partner, with 7.5 million people against over 600,000 in Montenegro and its economy is 10 times bigger.
Most ethnic Montenegrins, 43 percent, are likely to choose independence, as will Muslims, Albanians and other minorities. The 32 percent ethnic Serbs are likely to back the union.
Under pressure from the EU, Montenegro agreed to referendum rules that say at least 50 percent must vote and at least 55 percent must choose independence for the result to be valid.
Are Montenegrins a separate nation or is it time to undo the 1918 union with Serbia some say was little more than annexation?
"You've always had those who wanted an independent state and those who say Serbs and Montenegrins are the same nation and should be in the same state," said senior researcher Milos Besic of Podgorica's Centre for Democracy and Human Rights.
"I don't think this referendum can resolve that. The division will exist, arguments will remain, for a couple of generations."
Kristof Bender of the European Stability Initiative said supporters of independence do not see the issue as breaking away from Serbia, but rather as reaffirming their statehood.
"These people often reproach Belgrade and say: 'What is this rhetoric about losing Montenegro? It was never part of Serbia."
"But in the unionist camp, some people identify very strongly with the Serbian identity, so they perceive independence as breaking up something that belongs together."
Analysts see few practical effects from a divorce. The two already have different laws, policy and currency, sharing only defence and diplomacy. Their joint parliament barely meets.
Bender said separation would allow both to focus more on their domestic problems and on pursuing EU membership.
Serbia this year also faces the loss of Albanian-dominated Kosovo province, adding to an impression of abandonment that plainly irks some Serbs.
Analysts said few Serbs saw Montenegro as a state with its own history, culture and distinct identity. They tended to view the independence drive as yet another breakaway bid.
"You mustn't forget that Belgrade was capital of the old socialist federation, and there was a similar feeling that Slovenia, Croatia, Macedonia and Bosnia broke away," Bender said. "Montenegro is now the last to go."