Conakry - The death toll from one of Guinea's deadliest road accidents shot up to 70 on Wednesday as five more people died overnight, state radio said.

"The toll is getting heavy, with 70 deaths," said Guinean Radio Television (RTG) citing hospital sources in the west African state.

Several other people were injured in the accident, which occurred when a lorry toppled into a lake while trying to cross a narrow wooden bridge.

Officials said the accident late on Monday near the town of Gueckedou, about 700km southeast of the capital was one of the worst in the west African country in decades.

Police said the lorry was overloaded, and have opened an investigation into the disaster.

Witnesses said most of the casualties were Guinean traders.

Due to insufficient public transport, trucks are often used to ferry people in parts of Africa. Bad roads have also contributed to high rates of fatal accidents.