Speaking in Sydney, Carney said the war in the Middle East represented "another example of the failure of the international order".

"Canada calls for a rapid de-escalation of hostilities and is prepared to assist in achieving this goal," he said.

"Canada reaffirms that international law binds all belligerents," he said.

The United States and Israel launched the attack on Saturday and quickly killed Iran's supreme leader, Ayatollah Ali Khamenei, two days after US envoys had been speaking to Iran in Geneva on a nuclear accord.

Since then, Iran has expanded its retaliatory missile and drone barrage across the Middle East, hitting on Tuesday a US consulate and base as the United States and Israel said they had pummeled key sites inside Tehran.

The regional war also took a growing toll on Lebanon, where Hezbollah, the armed Shiite Muslim movement that long had Tehran as a benefactor, launched drones and rockets at Israel in retaliation for Khamenei's slaying.

Carney has backed the Israeli-US strikes targeting Iran, saying Tehran had failed to dismantle its nuclear programme and cease support for militant groups.

He expressed "regret" on Wednesday that international efforts had failed to disarm Iran.

But he noted that "the United States and Israel have acted without engaging the United Nations or consulting with allies, including Canada".

Carney's comment came on the second day of an official visit to Australia, a trip aimed at bringing in investment and deepening ties with a fellow "middle power" partner.

He will address a meeting of the Lowy Institute think tank later in the day, while on Thursday he will meet with Prime Minister Anthony Albanese and address parliament in the capital Canberra.

The trip is part of a multi-country tour of the Asia-Pacific aimed at reducing reliance on the United States -- a hedge against what Carney has described as a fading US-led global order.

"Canada is actively taking on the world as it is, not passively waiting for a world we wish to be," he told journalists in Sydney.