MONROVIA (Reuters) - Tension, a planned opposition boycott and fresh memories of a day of deadly clashes hang over Liberia's presidential election run-off on Tuesday, which incumbent leader Ellen Johnson-Sirleaf is poised to win.
Johnson-Sirleaf is set to secure a second term in the poll, the West African state's first locally organized presidential contest since a civil war, after her rival Winston Tubman withdrew in protest against alleged fraud in the first round.
At least one person was shot dead after Tubman supporters clashed with Liberian and United Nations security forces in the capital Monrovia on Monday. A Liberian police officer was detained by U.N. peacekeepers after he admitted to firing live rounds during the clash, Liberia's police inspector said.
"We don't want any trouble. But monkey and baboon not getting along," said a Monrovia resident who called himself Tarr. Liberians have nicknamed Johnson-Sirleaf 'monkey' and Tubman 'baboon' and frequently used stuffed animal mascots during campaigning.
Human rights watchdog Amnesty International called for a thorough investigation of the killing and urged restraint through the rest of the election process.
"All political candidates must ensure their supporters respect the law and make clear to their supporters that those responsible for ordering or carrying out human rights abuses will be held accountable," said Lucy Freeman, a West Africa researcher for the group.
Tubman, a Harvard-educated former U.N. ambassador, seized on the clashes to criticise Johnson-Sirleaf.
"It shows to you why the Liberian people are determined to get rid of this leader. She is somebody who will use violence against peaceful people," he said.
The government called the rally an illegal provocation and urged voters not to be intimidated on election day.
On Tuesday U.S. President Barack Obama called on Liberian security forces to show restraint and allow peaceful protest, and he warned against any voting violations.
"Those gains (to consolidate democracy) must not be set back by individuals who seek to disrupt the political process," he said. "The international community will hold accountable those who choose to obstruct the democratic process."
The vote is due to gauge the West African state's progress since civil war ended in 2003 and pave the way for new investment, but fears are rising it could instead kick off open-ended political turmoil.
Liberia is one of the world's poorest countries, with over half of its people surviving on less than 50 U.S. cents a day. Fourteen years of intermittent fighting killed nearly a quarter of a million people and has left its infrastructure in ruins.
Johnson-Sirleaf took nearly 44 percent of the first round vote on October 11 and has since won the backing of the third-place finisher, former warlord Prince Johnson.
Tubman -- who won roughly 33 percent in the first round -- said last week he would withdraw from the race and called for a boycott because of evidence of fraud. He said he would only be willing to participate in a second-round if it were delayed by two to four weeks and counting procedures were amended.
International election observers called the October 11 vote mostly free and fair, and the United States, the United Nations, regional bloc ECOWAS and the African Union have all criticised Tubman's decision.
Many of his supporters are unemployed former fighters.
Johnson-Sirleaf became Africa's first freely elected female head of state in 2005, and has been internationally praised for reducing the country's debt and maintaining peace. But she faces criticism within for the slow pace of development.
Analysts had anticipated that a smooth election would trigger a surge in foreign investment in resources such as iron ore and oil, which have already attracted major firms including ArcelorMittal, BHP Billiton and Anadarko Petroleum.
Editing by David Lewis