The Australian Human Rights Commission has warned Peter Dutton’s proposal to lower the bar for stripping people convicted of terrorism or related offences of Australian citizenship could render people stateless and would be retrospective in application – in possible violation of international law or the rule of law.

The warning echoes concerns of the Law Council of Australia about a bill likely to be a top Coalition priority in 2019, given Scott Morrison has nominated national security as the most important unfinished business before the federal election.

In November, the government proposed to give the home affairs minister the power to strip Australian citizenship from people convicted of any terrorism offence, removing the current requirement that they must also have been sentenced to at least six years in prison.

The standard for stripping a dual citizen of Australian citizenship would also be lowered, so the minister would only need to be “reasonably satisfied” that a person would have another citizenship.

The change would increase the chances the minister might strip citizenship from a person who was not in fact a dual national or in circumstances where their foreign citizenship was disputed, as occurred in the case of 27-year-old Isis fighter Neil Prakash who was disowned by both Australia and Fiji.

On Monday, Bill Shorten labelled the revocation of Prakash’s citizenship a “summer stunt”.

Shorten told reporters in Jabiru that he did not want Prakash back in Australia. But he accused the government of “fluffing the legal procedures” by not “[squaring] it off with the Fijian government”.

In its submission to the parliamentary joint committee on intelligence and security, the AHRC urged parliament to block the bill because it was not a “reasonable, necessary and proportionate” limitation on human rights.

The AHRC warned the minister could be “reasonably satisfied” a person had a foreign citizenship and nevertheless be “mistaken about that fact” – rendering the person stateless.

The new bill would prevent a person stripped of citizenship from applying to a court to prove they did not hold a foreign citizenship, allowing such a ministerial error to stand because merits review to the administrative appeals tribunal is also banned.

The AHRC said this “raises a serious risk of conflict” with the statelessness convention and the Universal Declaration of Human Rights, which states that “no one shall be arbitrarily deprived of his nationality”.

The AHRC said the power to strip Australian citizenship should be reserved for “the most exceptional circumstances, where the gravest criminal conduct also repudiates one’s allegiance to Australia”, arguing the bill’s stated purpose of upholding the integrity of Australian citizenship was “too general or vague”.

In a separate submission, George Williams, dean of the University of New South Wales law school, and senior research associate Sangeetha Pillai argued that “minor convictions” could trigger loss of citizenship.

These included donating money to an overseas organisation reckless as to whether it was a terrorist organisation or entering an overseas conflict zone designated a no-go area even if the person did so without any intent to cause harm.

The AHRC noted the new citizenship stripping powers would apply to offences committed after 12 December 2005.

It said this “in effect” imposed a heavier penalty for criminal conduct than existed at the time of the offence, and noted that people stripped of citizenship would likely be held in immigration detention unless and until they were deported, an “extremely severe” consequence.

The AHRC warned that children as young as 10 could have their Australian citizenship stripped, and stripping citizenship from parents might cause children to lose theirs too.

Williams and Pillai argued that citizenship removal was of “minimal utility as a national security device”.

Both submissions noted that national security is already protected by a regime of executive control orders and preventative detention orders.

The committee is due to hold a public hearing on 30 January.