A presidential bid by a popular politician in the Yugoslav republic of Montenegro has failed. Officials say voter turnout was too low to validate the election. Some observers say the annulment is blamed on an opposition ballot boycott and a high profile sex scandal.

Although he appeared to have collected most votes, former Prime Minister Filip Vujanovic said he had failed in his bid to become president as less than half of Montenegro's nearly 460,000 voters bothered to cast their ballots.

The often criticized 50 per cent rule was instituted by former Yugoslav President Slobodan Milosevic's regime in what was seen as an effort to ensure its success in both Serbia and Montenegro, the last remaining republics of Yugoslavia.

Election observers say additional factors for Sunday's ballot failure were the decision of the main opposition to boycott the election, as well as apparent voter apathy over a sex scandal involving officials.

The scandal broke last month after special Montenegrin police units arrested Deputy State Prosecutor Zoran Piperovic and three other men as part of an investigation into organized prostitution and trafficking in refugees.

Analysts believe the case is significant because Montenegro's authorities have not prosecuted senior officials for corruption or involvement in widespread organized crime over the past decade.

The testimony of an allegedly sexually abused and tortured 19-year-old Moldovan woman was considered crucial. She escaped her captors.

Mr. Vujanovic has pledged to arrest anyone who is involved in these and other organized criminal activities. But opposition parties have questioned his words, because Mr. Vujanovic is a close ally of Milo Djukanovic, who resigned last month as President to become Prime Minister.

Opponents and even some Western officials say Mr. Djukanovic was involved in corruption or at least shady business practices. The opposition also questions the pro-independence policies of both Mr. Djukanovic and presidential candidate Vujanovic.

They have reluctantly supported a Western backed interim agreement with Serbia to replace the current Yugoslavia with a new country to be named "Serbia and Montenegro." The arrangement lasts for three years after which both republics can decide on independence.

Mr. Vujanovic has pledged to eventually move Montenegro, as an independent country, into NATO and the European Union. The republic of 650,000 people has already established an independent monetary policy and embraced the Euro as its preferred currency. Yet, Mr. Vujanovic, 48, will have to wait to carry out his ambitious plans of Western integration, as new presidential elections will have to be called.

There is concern within the Council of Europe and the Organization for Security and Cooperation in Europe that Montenegro's current political stalemate will lead to more instability in the often volatile Balkans and slow down reforms to tackle poverty and crime.