Australia summoned the Israeli ambassador on Thursday to explain how three Australian passports were used by suspected Mossad assassins to murder a top Hamas commander in Dubai.
Prime Minister Kevin Rudd said Australia "will not be silent on the matter" after three Australian passport-holders were named among 15 new suspects linked to last month's Cold War-style killing of Mahmud al-Mabhuh.
"If Australian passports are being used or forged by any state, let alone for the purpose of assassination, this is of the deepest concern and we are getting to the bottom of this now," Rudd told public broadcaster ABC.
"We will not leave a single stone unturned."
Rudd said Australian officials had worked through the night after Dubai police named Australian, British, French and Irish passport-holders among the new group of suspects.
Dubai police strongly suspect Mossad, the Israeli spy agency, of carrying out the assassination in a luxury Dubai hotel where al-Mabhuh was found dead in his room after an apparently well-planned hit.
Rudd said he had discussed the development "at length" with Foreign Minister Stephen Smith, who will meet the Israeli ambassador later.
Australia's ambassador in Tel Aviv was also seeking a meeting with Israeli officials.