Australia followed Britain's lead by expelling an Israeli diplomat after investigations concluded four Australian passports used in the assassination of a Hamas commander were almost certainly forged by Mossad, the Israeli intelligence service. The move increases the international pressure on the Jewish state to acknowledge its role in the killing in Dubai last January.

Stephen Smith, the Australian foreign minister, said he had given the diplomat a week to leave the country.

The diplomat was not named, although reports suggest he was the Mossad representative at Israel's embassy in Canberra.

Australia's response has dashed hopes in Israel that Britain's ejection of one its diplomats from London in March marked the final word in the assassination of Mahmoud al-Mabhouh.

With Germany, France and Ireland, the three other countries unwittingly caught up in the saga, yet to make a formal response there will be concern in Israel that the fallout from the scandal could spread still further.

According to Dubai police, at least 32 individuals carrying forged passports were involved in the killing of Mr Mabhouh, who was smothered in his hotel room on January 19. The investigation concluded that 12 or more of the assassins passed themselves off as British.

France and Germany are understood to have been reluctant to expel diplomats but could now reconsider their positions in the wake of the Australian decision. Ireland is also considering similar action, a diplomatic source said.

For Israel, such coordinated action would turn a bilateral dispute with Britain into an unprecedented foreign policy crisis with countries considered to be close allies of the Jewish state.

Israel is already concerned that Britain still refuses to allow Mossad to send a new station chief to London unless assurances are received that British passports would never again be forged in an intelligence operation. Israel has refused to confirm or deny its involvement in the Dubai assassination.

Using similar wording to David Miliband, the former Foreign Secretary, Mr Smith told the Australian parliament that an investigation concluded that the passports could only have been forged by a state intelligence service.

"These investigations and advice have left the government in no doubt that Israel was responsible for the abuse and counterfeiting of these passports," he said. "We do not regard these actions as the actions of a friend."

Mr Smith also revealed that Mossad had previously forged Australian travel documents and had given "confidential undertakings" not to do so again.

Unlike in Britain, Australia's opposition did not welcome the expulsion, accusing the government of pandering to Arab states in the hope of winning their support for an Australian bid to win a seat on the United Nations' Security Council.

Israel said it regretted the Australian decision.

Bonnie Malkin in Sydney and Adrian Blomfield in Jerusalem
Published: 3:44PM BST 24 May 2010