At least five people were killed and more than 50 injured on Wednesday when a train slammed into a public bus before dawn near Tunis, the Tunisian interior ministry said.

The articulated bus was torn in two when it was struck on the tracks at around 6:00 am (0500 GMT) near Sidi Fathallah, about 10 kilometres (six miles) south of the Tunisian capital.

The ministry said in a statement that five people, including a child, were killed and another 52 taken to hospital, many with serious injuries.

Among the injured were eight soldiers, said Mosaique FM radio station.

The bus belonged to the public transport service of the town of Nabeul, about 50 kilometres (30 miles) south of Tunis.

President Beji Caid Essebsi paid a visit to some of the injured at the Ben Arous hospital in southern Tunis.

"An investigation has been opened to understand the circumstances... and to determine responsibility," said Hassen Miaadi, the director of communications for the national railway company.

Authorities in Tunisia have called for greater caution on the roads following accidents including a collision between a bus and a lorry in August that killed 16 people and injured 85.

In a 2015 report from the World Health Organization, Tunisia had the second worst traffic death rate per capita in North Africa behind war-torn Libya.

Tunisia logged 24.4 deaths per 100,000 inhabitants, according to data from previous years, less than Libya's 73.4 but far more than 2.9 in the United Kingdom.