A bus convoy of Muslim voters in northern Sri Lanka came under fire and stone-throwing on Saturday, a local watchdog group said.

The incident came hours before a presidential election could allow the Rajapaksa family, who ruled the country with an iron fist for a decade, to return to power.

About 16 million Sri Lankan voters were invited to the polls on Saturday to vote in a presidential election that is expected to see a fierce contest between Gotabaya Rajapaksa and Sagit Premadasa, the current ruling party candidate.

Hours before polling began, gunmen opened fire on the bus convoy but no casualties were reported, authorities said.

A police official said the attackers burned tires on the road and set up roadblocks to ambush the convoy of more than 100 buses in the north of the island.

"Gunmen opened fire and threw stones" at buses carrying Muslims from the coastal city of Puttalam to neighboring Mannar province, where they registered to vote, a police source in Tantirimally, a city about 200 km north of the capital Colombo, said.

"At least two buses were injured but there were no fatalities," the official said.

About 16 million Sri Lankan voters were called to the polls on Saturday to vote .

Tensions and attacks
Sri Lanka saw tensions between Muslims and Christians earlier this year.

On April 21, eight attacks on churches and hotels coincided with Easter Christians, killing 290 people and injuring more than 500.

The day after the attacks, the authorities declared a two-month state of emergency, extended for another month on June 22.

The incident came as the army, which was led by Gautabaya Rajapaksa under his brother Mahinda Rajapaksa (2005-2015), was confronted with police in the mainly Tamil Jaffna region in the north of the island.

Police told the electoral commission that the army was illegally blocking roads, which could deter voters from voting in these non-pro-Rajapaksa areas.

"After informing the military that the erection of roadblocks was illegal during a national election period, they removed them," police said in a statement.

Police sources said they had warned all local military commanders that any interference in the elections would be reported and punished.