Djukanovic also rejected allegations of crime and corruption, saying "they (opposition) have been shooting the same target for 20 years and every time they end up in a fiasco."
In accusing Djukanovic, his main opponent, Miodrag Lekic has described Montenegro as "a country of captured institutions, where some individual and groups behave as if they were outside of the legal system."
Djukanovic was in the past under investigation by Italian prosecutors who suspected his government of a multi-million-dollar cigarette smuggling operation during international sanctions imposed on Serb-led Yugoslavia its 1990s-era warmongering.
An election monitoring group, Center for Monitoring, said that 33.4 percent of voters cast ballots in the first six hours of voting. Initial, unofficial results are expected few hours after the polls close on Sunday evening.
Jovana Gec contributed from Belgrade, Serbia.