At least 53 people died when a passenger bus collided with a truck carrying tomatoes on a Ghana highway, police said Thursday after one of the country's most deadly road disasters.

The head-on collision between the government-operated bus heading to the northern town of Tamale and the cargo truck happened Wednesday evening.

Nigerian President Muhammadu Buhari will travel to Accra on Monday to discuss regional security with his Ghanaian counterpart, John Dramani Mahama, his office said in a statement.

During the one-day official visit Buhari, who on Saturday marked his first 100 days in office, will also discuss trade relations with Ghana, his office said.

Protesters from one of Ghana's biggest slums clashed with police in the capital Accra on Monday, after city authorities demolished shanties as part of measures to combat heavy flooding.

Riot police fired teargas at the demonstrators from the Old Fadama slum, popularly known as Sodom and Gomorrah, and about 20 people were arrested during the altercation.

Ghana's President John Dramani Mahama called for national unity on Wednesday as he led a memorial service for more than 150 people killed in a petrol station fire and heavy flooding.

"There is plenty of blame to go around... We should invest our time in taking appropriate strategy to prevent (a) future occurrence," he said during the two-hour, multi-faith ceremony.

More than 150 people have now died in a devastating petrol station fire and heavy flooding in Ghana's capital, Accra, the country's Red Cross said on Friday.

"As at yesterday (Thursday) we have recovered more than 150 corpses. Sixty people have been taken to the hospital," disaster management coordinator Francis Obeng told AFP.

At least 90 people were killed in a fire at a petrol station in Ghana's capital, Accra, as they sought shelter from heavy rains that caused widespread flooding, emergency services said Thursday.

The fire broke out at the filling station in the Kwame Nkrumah Circle area of the city late on Wednesday night and is thought to have spread from a nearby residence.

The younger brother of a leading figure in Ghana's main opposition party appeared in court on Tuesday charged with the murder of a politician who died after an acid attack that shocked the nation.

Gregory Afoko, whose elder brother Paul is national chairman of the New Patriotic Party (NPP), pleaded not guilty before magistrates in the capital Accra.

One person has been arrested in Ghana after a leading member of the country's biggest opposition party was attacked with acid and later died, the police said on Friday.

Police spokesman for the Upper East region, Thomas Agbanyo, said a man was detained on suspicion of carrying out the attack on Adam Mahama and another is at large.

Togo's presidential election on Saturday saw low turnout, likely boosting President Faure Gnassingbe chances of winning a third term and extending his family's grip on power into a second half-century.

The opposition's prospects of unseating the president were considered poor heading into the vote in the tiny west African nation. 

Three people have died and 14 others required medical treatment after inhaling toxic fumes at a gold mine in Ghana, the company running the operation said on Friday.

"We can confirm that three people have died out of the inhalation of toxic fumes from our underground operations," said a spokesman for the Shaanxi Mining Company Ltd, Maxwell Wooma.