Sidi Yahya Tunis, a spokesperson for the opposition All People's Congress (APC) said one of its supporters was killed by police. A police spokesperson declined to comment, saying there would be a news conference later.

"We had asked our supporters to converge at our party headquarters. When they started coming the police advanced and tried to disperse them," said Tunis.

Videos shared on Twitter showed civilians carrying an unconscious man, who appeared to have been shot in the neck. Reuters has not verified the footage.

A mortuary in the city centre of the capital Freetown said it had picked up one body from the area with gunshot wounds.

There have been concerns of unrest in the run-up to the poll, similar to deadly anti-government protests that broke out last August. But in a Tuesday evening address to the nation, Bio had pledged to act decisively against any violence.

The United Kingdom, the United States, Ireland, Germany, France and the European Union on Wednesday noted reports of election-related violence in a joint statement and urged all sides to remain peaceful.

Around 3.4 million Sierra Leoneans are expected to vote on Saturday in the fifth presidential election since the end of a 1991-2002 civil war in which more than 50,000 were killed, hundreds maimed and hundreds of thousands displaced.

The poll comes against a backdrop of frustrations over growing economic hardship in one of the world's poorest countries.

Bio, 59, is seen as the frontrunner among 13 presidential candidates. His main challenger is the APC's Samura Kamara, who came a close second in the last election in 2018.

"ALL I WANT IS PEACE"

On the campaign trail, Kamara's party has criticised Bio's handling of the economy and soaring prices. The ruling party has blamed economic woes on external factors such as the COVID-19 pandemic and the war in Ukraine.

While campaigning was generally peaceful until now, the opposition has complained of attacks and harassment in ruling party strongholds in the southeast.

The ruling party has meanwhile complained about attacks on their supporters in southern Pujehun District and in the opposition's northern stronghold.

Some voters have been alarmed by rhetoric from main parties.

"All I want is peace. I am scared by the high level of hatred I see being exhibited on social media by political extremists on both sides," said a student at the University of Sierra Leone, who requested to remain anonymous.

Voters will also elect members of parliament and local councillors across the West African state.

(Reporting by Umaru Fofana Writing by Umaru Fofana and Sofia Christensen; Editing by Sharon Singleton)

By Umaru Fofana