Australia on Saturday stepped up pressure on Israel over fake passports linked to the murder of a top Hamas commander, saying it is yet to receive a satisfactory explanation. <br/><br/>Prime Minister Kevin Rudd said his centre-left government had an absolutely hard line on defending the integrity of its passport system and took seriously allegations that suspected Mahmoud al-Mabhouh assassins had stolen Australian identities. <br/><br/>Mr. Rudd said, the Foreign Minister met the Israeli ambassador on Friday, but that the explanation he gave for the identity scandal was not satisfactory.<br/>