Laws which allow the automatic stripping of an Australian’s citizenship contain a high risk that someone may be left stateless, the president of the Law Council has said, amid a growing standoff between Australia and Fiji over the Isis recruiter Neil Prakash.

Arthur Moses SC said Prakash’s case demonstrated the concerns the council had raised in 2015 when the Australian government introduced the legislation, and raised “serious questions” regarding its process.

Last week it was revealed the Australian government had revoked Prakash’s Australian citizenship because of his terrorism affiliations and actions, on the understanding he was a dual national of Fiji.

However, Fijian immigration authorities said they have no record of Prakash visiting Fiji, being a citizen, applying for citizenship or having someone apply on his behalf.

The home affairs minister, Peter Dutton, maintains the government’s legal advice – that Prakash is Fijian – is correct.

“If Prakash is in fact not a Fijian citizen, this raises serious questions regarding the automatic loss of citizenship under Australian law which requires a person to be a national or citizen of a country other than Australia,” Moses said on Friday. “This is an issue that needs to be properly investigated and respectfully discussed with Fiji.”

Moses said loss of citizenship should only occur after a criminal conviction, and it should not be automatic. “[It] should require a ministerial decision that considers whether the offender poses a substantial risk to Australia’s national security, as well as our international legal obligations,” he said.

“The minister’s decision should afford procedural fairness and be subject to judicial review.”

The Law Council has also previously warned about proposed legislation a minister could strip a convicted terrorist of Australian citizenship regardless of the severity of the conviction and need only be “reasonably satisfied” that the person had another citizenship.

The Labor party has called for Dutton to release the legal advice which he claims said Prakash held Fijian citizenship.

“Dual citizens who choose to be involved in terrorism forfeit the privileges of Australian citizenship, and I remain committed to enforcing the legal provisions that remove them,” Dutton said on Saturday.

However, after it emerged Fiji had no record of Prakash, Dutton sought to distance himself from the decision, releasing a statement which said the loss of citizenship occurred “automatically” after assessment by the Citizenship Loss Board.

The Citizenship Loss Board “comprising senior officials from several government departments, law enforcement and security agencies, examined the requirements for cessation of Australian citizenship in relation to Mr Prakash, namely: that he had been in the service of a declared terrorist organisation, Islamic State; that he satisfied age requirements as someone who is older than 14 years; and that he was a citizen of another country,” Dutton said.

“Neither the Citizenship Loss Board nor I make decisions on whether an individual ceases to be an Australian citizen, as the provisions operate automatically by virtue of a person’s conduct.”

Dutton also said the government had been in close contact with Fiji about Prakash, despite the head of Fiji’s immigration department telling Guardian Australia he learned of the situation through the media and was still yet to hear from the Australian government.

Moses said the government needed to ensure there was a “proper basis” for the loss of citizenship linked to national security, “which does not lead to uncertainty or disputes with our allies”.

“When an announcement of international and national importance is made, the government must ensure it is not premature and is verified.”