Liberian President Ellen Johnson Sirleaf is poised to win a second term in a run-off marked by low turnout after a deadly shooting that her rival says was an assassination bid against him.
Amnesty International called for an investigation into the shooting in which the opposition says up to eight of its supporters were killed on Monday, casting the shadow of Liberia's bloody past over the west African country's second post-war polls.
Sirleaf's challenger Winston Tubman, who cried foul after trailing the Nobel Peace laureate in last month's first round, has accused his rival of using her security forces to try to assassinate him during the opposition rally.
US President Barack Obama dismissed Tubman's fraud concerns as baseless and scolded him over his boycott call.
Whether heeding Tubman's call or fearful of a repeat of Monday's deadly incident, voters turned out in small numbers for an election that looked certain to return the 73-year-old Sirleaf to office.
No lines remained as polls closed on Tuesday night. The electoral commission said no incidents were reported during the day and counting began immediately.
"I have come to vote, but I am not happy for what happened yesterday," said Rita Queegbay, 39, at a polling station in a Monrovia suburb earlier in the day.
"After all we are all Liberian and no-one should be happy seeing other Liberians being killed."
UN peacekeepers kept a strong presence around the city during the vote, and a UN helicopter circled overhead.
Tubman said he had unconfirmed reports that at least eight of his supporters were shot dead after clashes broke out with riot police on Monday who sought to prevent his rally from turning into a march.
AFP journalists saw two bodies with gunshot wounds to the head.
Tubman said police had warned him not to embark on the unauthorised march, but before protesters could return to the party compound, they were sprayed with tear gas, which continued even as the crowd moved back.
Police have said the Congress for Democratic Change supporters were armed and had fired the first shot, which Tubman denies.
"I was getting out of the car, a young man pushed me back and ... a bullet that we believe was aimed at me by a sniper hit him instead of me, and he died," Tubman told international journalists in an interview at his home.
"I am of the belief that they (police) were acting under orders, and those orders indicated they were ordered to eliminate me."
Tubman, a Harvard-trained former diplomat whose running mate is 2005 runner-up and former football star George Weah, was confident of victory before the October 11 first round.
However he finished more than 10 percentage points behind Sirleaf, and claimed the ballot was riddled with irregularities, despite the vote being given a clean bill of health from hundreds of local and foreign poll monitors.
Tubman's boycott earned him little sympathy abroad, and in a statement issued after the election-eve violence, Obama said important gains by Liberia "must not be set back by individuals who seek to disrupt the political process".
Sirleaf's fellow Liberian Nobel laureate Leymah Gbowee turned out to vote, saying the election was a "defining moment" for her country's fragile democracy.
"Liberians lived in fear for so many years and today people ... have defied fear and intimidation and stepped out to vote," she said.
