Anthony Albanese has confirmed that three Australians were on a US submarine that sank an Iranian warship, after the Labor government earlier refused to comment on reports that emerged on Thursday.

The prime minister said the Australian defence force personnel were on the submarine as part of an Aukus training program.

But he maintained that Australian forces were in compliance with international law, and said: “No Australian personnel have participated in any offensive action against Iran.”

Asked about implications for international law in the US and Israeli strikes on Iran, Albanese said Australia was “comfortable” with assessing that Tehran posed a threat on three levels.

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“We wouldn’t normally confirm such an issue, but given our NSC [national security committee of cabinet] meetings, in the public interest, I can confirm that there were three Australian personnel onboard that vessel,” Albanese told Sky News Australia on Friday.

“I can confirm also, though, that no Australian personnel have participated in any offensive action against Iran. These are longstanding third-country arrangements that have been in place for a long period of time. And what they do is ensure that Australian defence force personnel, where they’re embedded in third countries’ defence assets, they act in accordance with Australian law, with Australian policy.”

The Australian government previously refused to disclose whether Australian sailors or officers were onboard the US attack submarine that torpedoed and sank an Iranian warship in the Indian Ocean on Wednesday, killing at least 87 people. But defence sources told the Guardian they believed that two Australians were on the submarine.

On Friday morning senior ministers initially refused to confirm those details, saying the government had a policy of not commenting on the location of ADF personnel.

Albanese said the three Australians onboard the submarine were there as part of the Aukus defence pact training program.

“It’s one of the big pluses behind the Aukus arrangements, Australian personnel getting experience across a range of assets, including being onboard nuclear-powered submarines, but also the exchange that’s occurring across the board.”

More details soon …