South Ossetia, the rebel region of the former Soviet republic of Georgia, Saturday officially banned any further campaigning on the eve of a tightly-contested run-off election for its next leader.

The first round on November 13 failed to produce an outright winner with South Ossetia's emergencies minister Anatoly Bibilov and ex-education minister Alla Dzhioyeva winning around 25 percent of the vote each.

Bibilov's inability to win anything close to an overall majority was a major surprise after his candidacy was unequivocally backed by the Kremlin and the outgoing leader of South Ossetia Eduard Kokoity.

"Any campaigning is forbidden today so the electorate can calmly decide for whom to vote," said the head of the South Ossetian election commission Bella Pliyeva.

Whoever wins Sunday's vote will find themselves recognised as president of South Ossetia only by Russia and a handful of far-flung states, with the West insisting that the Caucasus region remains an integral part of Georgia.

The elections were the first leadership polls in the breakaway statelet since Russia recognised it as independent in the wake of Moscow's 2008 war with Tbilisi over South Ossetia and another breakaway region Abkhazia.

The United States and the European Union both dismissed the first round of polls as illegitimate with Georgia denouncing them as a "cynical act of pseudo-democracy".

The electorate in South Ossetia is also tiny -- the rebel authorities say its population is 70,000 but Georgian officials argue that the figure is no more than 15,000 due to the expulsion of ethnic Georgians and migration.

In apparent attempt to bolster Bibilov's position ahead of the vote, Russian President Dmitry Medvedev met the candidate in southern Russia last week.

Dzhioyeva, the only female candidate in the first round, appears to have benefited from the local authorities' visible failure to properly rebuild South Ossetia's central town of Tskhinvali after the war.

Kokoity, a former wrestling champion who has dominated South Ossetia for a decade, has also made no secret of his hostility towards her candidacy.

In an interview with Russian newspaper Komsomolskaya Pravda, he said it was "excluded" that a woman could win.

"We have good relations with women in our society. But the Caucasus are the Caucasus," he said.