More than 20 people are feared dead after a passenger boat capsized on Lake Volta in Ghana. Officials say 20 people have been rescued.

Officials say it is not yet known how many people were on board the vessel when it sank Monday.

Boat Owners Association Chairman Kofi Baako says it will take three days to determine the actual number of casualties.

Reports say the boat was traveling across Lake Volta from Drubin, in the Northern Region, to Yeji, in the Brong Ahafo Region, when it was hit by a storm.

The incident is the second major boat disaster in five months on Lake Volta, which covers 8,500 square kilometers, more than three times the size of Luxembourg.

The Brong Ahafo Regional Coordinator of the National Disaster Management Organization, Nana Atta Afena, told a local radio station the search is still underway.

"That particular boat has been marked as not very competent to be on the Volta Lake," said Afena. "Because Ghana Maritime Association has declared that particular boat unfit or not safe to travel on that river, but what I heard was that there was a rainstorm and there was a heavy wind and that resulted in that accident."

Afena also says boat accidents are common on Lake Volta, adding that many are due to overloading and sub-standard vessels.

Last April, a boat carrying about 120 people, twice the number of authorized passengers, capsized in the Afram Plains region, whiles traveling across the lake.

The actual number of people who died in that accident is yet to be established, as the local people disputed the official death toll of about 10. A committee set up by the government to investigate that incident has not submitted its full report.