A Tunisian policeman was shot dead Wednesday by two assailants on a motorbike in the coastal resort of Sousse where a jihadist gunman killed 38 tourists in June, a senior security official said.

"Unknown assailants fired on three policemen on a road. One of them was hit and died in hospital," Rafik Chelly, secretary of state for national security, told AFP.

"An investigation is under way. We can't say any more," said Chelly, without being able to clarify if the attack was the work of jihadists.