Most of those killed in a massacre at a Tunisian beach resort claimed by the Islamic State group were British, the Tunisian Prime Minister Habib Essid said on Saturday.

"The majority are British," he told a news conference. "After come the Germans, then the Belgians and then other nationalities," he said, adding that there were also French among the victims.

He also revised an earlier death toll from 39 to 38, saying the previous figure had also included the dead gunman who had attacked the popular beach resort of Port el Kantaoui.