In a major anti-terror operation, Australian police have arrested four men they say were planning a suicide attack on an army base in the country.Hundreds of officers were involved in a series of dawn raids in the southern city of Melbourne. Those detained, suspected of having links with an Islamist militant group in Somalia, include Australians of Somali and Lebanese descent. “Details of the planning indicate that the alleged offenders were prepared to inflict a sustained attack on military personnel until they themselves were killed, “ said Federal Police Acting Chief Commissioner Tony Negus. “The investigation has also identified alleged travel of Australian citizens to Somalia, to participate in hostilities in that country.” After months of surveillance, police believe the plan was to mount an attack with firearms not bombs. Had it been implemented, authorities say the alleged plot would have been the most serious terrorist act ever on Australian soil.