Gunmen fired at buses carrying minority Muslim voters on Saturday as Sri Lankans elected a new president, with the powerful Rajapaksa clan eyeing a comeback seven months after the island was hit by extremist attacks.

Minority Tamils and Muslims are seen as crucial in the close election, and Saturday's attack in the northwest of the island — in which no one was injured — was likely aimed at deterring people from voting.

The assailants set fire to tyres on the road and set up makeshift roadblocks before shooting at and pelting with stones two vehicles in the convoy of more than 100 buses taking people to their home district to vote, police said.

In the Tamil-dominated northern peninsula of Jaffna, meanwhile, police said they arrested 10 men they suspected of "trying to create trouble", while also complaining that the army had illegally set up roadblocks that could stop people getting to polling stations.

Such tactics are nothing new in Sri Lanka, which emerged from a horrific civil war only a decade ago. At the 2015 election, there was a series of explosions in the region that activists said were aimed at reducing turnout.

This time, there were long queues outside polling stations even before voting began.

Supporters from rival parties, meanwhile, clashed in a tea plantation area 90 kilometres east of the capital Colombo, with two people taken to hospital with knife wounds, the election commission said.

Terminator vs Padman

Some 85,000 police were on duty for the election with a record 35 candidates running for president, an office with considerable power similar to the French political system, with close to 16 million eligible voters.

Results could come as early as Sunday.

One of the two frontrunners is grey-haired retired army lieutenant colonel Gotabaya Rajapaksa, 70, almost five years after his charismatic but controversial elder brother Mahinda Rajapaksa lost power after a decade as president.

Dubbed the "Terminator" by his own family, "Gota" is promising an infrastructure blitz and better security in the wake of the Islamist attacks in April that killed 269 people.

"Gotabaya will protect our country," construction worker Wasantha Samarajjeew, 51, said as he cast his ballot in Colombo.

He main rival is Sajith Premadasa, 52, from the governing liberal United National Party (UNP), son of assassinated ex-president Ranasinghe Premadasa.

He is also pushing development and security but also free sanitary pads for poor women, earning him the nickname "Padman" after a famous Bollywood movie.

The Rajapaksas are adored by Sri Lanka's Sinhalese majority for defeating the Tamil Tigers and ending a 37-year civil war in 2009 in which around 100,000 people lost their lives.

For the same reason, they are detested and feared by many Tamils, who make up 15 percent of the population. The conflict ended with some 40,000 Tamil civilians allegedly killed by the army.

During Mahinda Rajapaksa's presidency, Gotabaya was defence secretary and effectively ran the security forces, even allegedly overseeing "death squads" that bumped off political rivals, journalists and others.

He denies the allegations.

Many Muslims in the Buddhist-majority country of 21.6 million are also worried, having already witnessed increased hostility since the April attacks, including hundreds of homes and shops being trashed.

Chinese subs

What also concerns Western countries, as well as India, is that strategically located Sri Lanka moved closer to China under Mahinda Rajapaksa, even allowing two Chinese submarines to dock in Colombo in 2014.

Beijing loaned and granted Sri Lanka billions of dollars for infrastructure projects under China's immense Belt and Road Initiative spanning Asia and beyond. Mahinda says credit was unavailable elsewhere.

Sri Lanka was forced in 2017 to hand Beijing a 99-year lease on the port of Hambantota after being unable to service a $1.4-billion Chinese loan, highlighting for critics the debt dangers of Beijing's scheme.

"Chinese entities were also credibly accused of fuelling corruption, illegally funnelling money to favoured political candidates, and inserting sovereignty-violating provisions into their infrastructure agreements," said Jeff Smith, a research fellow at US think tank the Heritage Foundation.

Western capitals "should give a fair chance to us", Basil Rajapaksa, another brother, told reporters. "They can't be monitors of this country. They must be partners."