By Matthew Price Belgrade

Presidential elections are to be held in Serbia in November, the third time in a little over a year that people have been asked to go to the polls to try to choose a president.

Two previous elections last year failed due to a low turnout and Serbia has been led by an acting president ever since.

Serbs went to the polls in October and December last year

The previous elections failed because of an old law brought in by the former Yugoslav president, Slobodan Milosevic.

That states that at least half the electorate have to vote for the ballot to be valid.

In October 2002, and again in December, elections failed because the 50% threshold was not reached.

Analysts said people were too tired of politics to vote and leading politicians were accused of deliberately running a negative campaign in order to keep the top candidate, a rival, from winning the post of president.

Politicial crisis

Although the 50% rule still stands for the election on 16 November, some analysts expect a different, more positive, style of campaign which should get voters out.

Earlier this month Serbia's two largest opposition parties called for early elections amid a deepening political crisis.

In a joint statement they said the situation was so "grave that only early parliamentary elections" could help.

There have been daily attacks on politicians and since the assassination of the former Prime Minister Zoran Djindjic in March the atmosphere has worsened.