Predators who commit serious crimes against children could also face mandatory minimum sentences, while repeat offenders would find it much harder to get bail.

Several new offences would also be created, targeting those who administer websites that distribute child sex abuse material.

The vast majority of child sex offences are state crimes, so the proposed shake-up of Commonwealth laws is largely aimed at pedophiles who offend online or overseas.

Attorney-General Christian Porter is furious about the leniency of penalties handed to pedophiles.

"It simply beggars belief that nearly a third of all child sex offenders who were sentenced last year were not required to spend a single day behind bars," Mr Porter said on Tuesday.

"And when jail terms were handed out, the average length of time that offenders spent in custody was just 18 months."

The coalition tried to pass similar legislation in 2017, but it was knocked back after Labor baulked at the inflexible nature of the mandatory sanctions included in the bill.

The federal opposition argued juries would be less likely to convict if they knew judges had no discretion on sentencing.

Labor generally opposes minimum mandatory terms, but has made some exceptions at both state and federal levels.

Mr Porter is urging the opposition to reconsider its stance.

"If ever there was a policy that needed Labor to rethink their position, this surely must be it."

Labor does appear open to reconsidering the bill.

"Every child must be kept safe," shadow attorney-general Mark Dreyfus told AAP.

"Labor strongly supports keeping children safe and holding these horrendous individuals to account."

The Australian Federal Police received 18,000 reports of child exploitation last year, which was almost double the number of complaints made the previous year.

Mr Dutton wants to get the bill through parliament as quickly as possible.

"It's not a silver bullet, but it sends a clear message of deterrence," he said.

"We need to be realistic about the threat and we need to lock up those people that are doing the wrong thing."

The proposed penalties will not apply to people aged under 18.

The legislation will be introduced to parliament next Wednesday.

Australian Associated Press