TAREK AMARA TUNISIAN military prosecutors said they had begun investigating a journalist on suspicion of "harming public order" for saying the president had asked the army to close a powerful labour union's headquarters, and a witness said the reporter had been arrested. The journalist, Salah Attia, told Al Jazeera on Saturday that President Kais Saied had asked the army to close the headquarters of the UGTT union and put political leaders under house arrest, but that the army had refused. "Police in civilian clothes arrested Attia in a cafe in the suburb of Ibn Khaldoun in the capital," the witness,…