Updated

Montenegro's opposition parties are claiming that a parliamentary election which resulted inconclusively was packed with irregularities.

Prime Minister Milo Djukanovic's long-ruling party won the most votes in the Sunday ballot, but without enough support to govern alone. Both the opposition and the Democratic Party of Socialists will now have to try form a governing coalition with several small groups represented in the 81-seat parliament.

The tense election was marked by the arrest of 20 people suspected of planning politically motivated armed attacks against Djukanovic and his supporters. Opposition leaders claim that thousands of their supporters were rounded up by the police on the election day.

Opposition Democratic Front leader Andrija Mandic said Monday that "the police junta did everything to keep Djukanovic in power."