The Queensland state government is set to appeal the sentence handed down to a man who kidnapped a seven-year-old girl from a Kmart store north of Brisbane and sexually assaulted her in bushland.

On December 18, Sterling Mervyn Free took the girl from the Kmart toy aisle in Westfield North Lakes to a bushland 30 minutes away, where he molested her before returning her to the shopping centre.

Earlier this month, Free was sentenced to eight years behind bars with possibility of parole in two years after pleading guilty to taking a child for immoral purposes, deprivation of liberty and indecent treatment of a child under 12.

The girl’s mother said in a statement that she was “disappointed with the sentence”.

“No child should ever have to go through this type of trauma, and no sentence will ever be long enough to make up for the ongoing effects this will have on her,” the girl’s mother said.

Child safety advocate Bruce Morcombe said at the District Court that the sentence was not enough to deter others.

“The bar needs to be sufficiently high to say to these other people, these other creeps that are out there that have fascination about our kids, don’t go there or you’ll be locked up for decades,” said Morcombe.

The state government will appeal the eight-year sentence given to the father-of-two, Attorney-General Yvette D’Ath told state parliament on Thursday.

“I understand there has been significant community interest in relation to the sentencing of Sterling Free,” D’Ath said in a statement on Twitter on the same day.

“I have decided to appeal the sentence on the basis it is manifestly inadequate.”