Child sex offenders could face life behind bars under laws to be re-introduced to federal parliament next week.

The proposed shake-up of sentencing laws is largely aimed at pedophiles who commit crimes online and overseas.

The laws, which contain mandatory minimum sentences, would also make it harder for offenders to get bail or parole.

"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," Attorney-General Christian Porter said on Tuesday.

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The coalition tried to pass similar legislation in 2017, but it was knocked back after Labor baulked at the mandatory sentences.

Home Affairs Minister Peter Dutton wants to get the legislation through parliament as quickly as possible.

"It's not a silver bullet, but it sends a clear message of deterrence," he told the Seven Network.

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