The boat, which had more than 100 villagers on board, was travelling to farmlands in Niger state, around 156 miles (250km) from the nearest emergency service.

Because of its remote location, it took several hours for responders to reach the scene in the Niger River on Sunday, although 30 people have been rescued.

Villagers have been asked to watch out for bodies floating in the river as at least 40 passengers remain missing, according to Niger State Emergency Management Agency spokesman Ibrahim Audu.

Niger governor Mohammed Umaru Bago described the accident as "shocking and sorrowful".

It is still not clear what caused the accident, but emergency services say it could be because of overloading, a hindrance to the boat's movement or the vessel's condition.

The number killed stood at 26 on Sunday, but rose after more bodies were found in the water on Monday morning.

Sunday's incident marked the second such major accident in the region in three months.

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In July, more than 100 people died when an overloaded boat capsized in a remote part of Niger state in what was one of the worst such disasters in recent years.

Nigeria is Africa's most populous country and a number of remote communities have no access to good roads, meaning river travel is the only way to get around.