Melbourne, Australia (CNN) -- Australia on Monday called for the expulsion of an Israeli diplomat over fake passports used in the assassination of a Hamas operative in the United Arab Emirates.
An investigation had confirmed that Israeli agents were behind the forgery of Australian passports used in the January 20 killing of Mahmoud al-Mabhouh, a founding member of Hamas' military wing, Foreign Minister Stephen Smith said.
The four Australians whose passports were used were victims of passport fraud and had nothing to do with the killing, he said.
Smith did not elaborate whom Australia wanted expelled from the Israeli diplomatic mission in Canberra but said diplomat has to leave within the week.
He briefed parliament on the results of the investigation Monday morning and said the forgeries were so sophisticated, only a state intelligence service could have carried them out.
"We regret the Australian decision, which is is not in line with the quality and the importance of our relationship," said Yigal Palmor, a spokesman for the Israeli Foreign Ministry.
Smith said the decision to call for the expulsion was made after consultation with the British, American and United Arab Emirates foreign ministries. The forgeries, he said, "are not the actions of a friend."
"Australia's relationship with Israel has always been founded on a basis of mutual respect and trust. But Israel's actions in this regard have undermined that respect and trust," Smith said, addressing lawmakers. "Mr. Speaker, the government takes this step much more in sorrow than in anger or retaliation. It is a decision taken in our national security interests."
Al-Mabhouh was found dead in his hotel room in Dubai. Police believe he was killed the night before and suspect the Mossad, the secretive Israeli foreign intelligence unit, was behind his killing.
Israel has a stated policy on security matters of neither confirming nor denying involvement.
"There is certainly no reason to think that the Mossad and not some other intelligence agency of another country operated there," Israeli Foreign Minister Avigdor Lieberman, however, told Israel Army Radio in March.
A total of 28 suspects have been identified by Dubai police. The suspects are believed to have acquired faulty passports to arrive in Dubai for the killing and then fled to other far-flung locations, police said.
The 26 named suspects do not include two Palestinians previously arrested in Jordan and returned to the United Arab Emirates.
The suspects used British, Irish, French, Australian and German passports.
In February, the European Union condemned the use of false EU passports in connection with al-Mabhouh's slaying.
Police in Dubai said toxicology results show al-Mabhouh was injected with succinylcholine, a drug used to relax muscles during surgery or as an anesthetic, before he was suffocated.
Signs indicated that al-Mabhouh resisted as he was being suffocated, police said.
CNN's Hugh Williams contributed to this report