SYDNEY, Sept 1 (Reuters) - An Australian

government-commissioned report said selfie-based age guessing

software could enforce a teen social media ban, but noted that

some groups experienced "unacceptable" levels of inaccuracy,

raising concerns about the December rollout.

The report, published by the government on Monday, said

photo-based age estimation products were broadly accurate, fast

and privacy-respecting but noted worsening results for people

near the age minimum of 16.

The findings foreshadow a mixed experience once the ban

takes effect in December: Caucasians three years over the age

cut-off can expect minimal disruption, but non-Caucasians and

teenage girls face challenges.

The experience may also be more complicated for social media

platforms from Meta's Instagram to Alphabet's

YouTube which, under the law, must show they are taking

reasonable steps to block users under 16 or face a fine of up to

A$49.5 million ($32 million).

The trial found high accuracy for people over 19 but those

up to three years on either side of the cut-off were in a "grey

zone where system uncertainty is higher".

Users aged 16 had an 8.5% chance of being estimated as

underage so they might need to be "diverted to supplementary

assurance methods, such as ID-based verification or parental

consent", the report said.

"While systems generally performed well across diverse user

groups, some showed reduced accuracy for older adults,

non-Caucasian users and female-presenting individuals near

policy thresholds," the report added.

Social media experts said the report raised questions about

whether the ban could work in three months.

"It seems like there are a lot of variations in accuracy,"

said Justine Humphry, a media researcher at the University of

Sydney who specialises in online safety.

"That variation is concerning, with the tight schedule

for the introduction of a system that will need to be robust and

working by the end of this year," she added.

Communications minister Anika Wells said the report proved

that "while there's no one-size-fits-all solution to age

assurance, this trial shows there are many effective options and

importantly that user privacy can be safeguarded".

($1 = 1.5389 Australian dollars)