Gunmen fired on buses carrying minority Muslim voters in northwest Sri Lanka on Saturday, police said, as an election official admitted failures to protect vulnerable communities ahead of presidential polls.
There were no immediate reports of casualties, but a police official said the attackers had burnt tyres on the road and set up makeshift roadblocks to ambush the convoy of more than 100 vehicles.
"The gunmen opened fire and also pelted stones," said a police official in Tantirimale, 240 kilometres (150 miles) north of the capital Colombo. "At least two buses were hit, but we have no reports of casualties."
Muslims from the coastal town of Puttalam were travelling to the neighbouring district of Mannar, where they were registered to vote, the official added.
Sri Lanka's minority Tamils and Muslims are seen as crucial to deciding a close contest between the two frontrunners -- housing minister Sajith Premadasa and the opposition's Gotabaya Rajapaksa.
One of three Election Commissioners, Ratnajeevan Hoole, said the authorities failed to provide adequate protection to internally displaced minority Muslims in the multi-ethnic northwest.
"They (the Muslims) asked for polling booths in the areas where they are living without having to travel a long distance to their original village to vote," Hoole said in a statement.
"They were sure that a disturbance like this would happen," he said, adding that his pleas for protection were not considered by the Election Commission, which works through majority decisions.
Police reinforcements rushed to the troubled area, cleared the road obstructions and escorted the convoy so passengers could cast their ballots.
The incident came as police and troops were locked in a tense standoff in the Tamil-dominated northern peninsula of Jaffna where residents complained about military roadblocks ahead of voting.
Police reported to the independent Election Commission that the army was illegally manning roadblocks that could discourage residents from freely travelling to polling booths.
"After bringing to the notice of the army that the roadblocks were illegal at a time of a national election, they have dismantled them," police said in a statement.
Police sources said they had also warned local military commanders that any disruption to the election would be reported to courts and offenders prosecuted.
The police also arrested 10 men who were unable to explain their presence in the Jaffna peninsula on the eve of voting.
"We suspect they were trying to create trouble during voting," a police official said.
Local media reports say there are fears that a strong military presence in Jaffna, the heartland of the island's Tamil minority, could influence voter turnout and favour Rajapaksa, a former defence ministry chief and brother of former president Mahinda Rajapaksa.