Australia's toughest laws for child sex offenses proposed in SA

South Australia is set to introduce the country's toughest laws on child sex offenses, meaning the state's worst pedophiles could be locked up for the rest of their lives.

The new laws would mean repeat offenders would only be released if the court was satisfied they could control their sexual instincts, and they would then undergo electronic monitoring.

The legislation would apply only to those who have been imprisoned for a child sex crime for a second time.

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SA Attorney-General Kyam Maher presented the bill to parliament with support from the opposition this afternoon.

"If you are a vile monster who prays on children you will now be facing the harshest penalties in this country," Maher said.

"If you commit these sorts of crimes against children you should be taken off the street for the longest possible period the rest of your natural life so you can't do this to other children."

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Sonya Ryan, who founded the online safety charity The Carly Ryan Foundation, said she was pleased to see real action being taken to protect the community and the most vulnerable.

"They pose a real threat to our children they are opportunistic offenders so they need to be managed appropriately," Ryan said.

The government said it was confident the laws would pass and should be in practice later this year. 

The legislation was introduced two months after the government promised to fast-track the legislation as part of a crackdown on serious repeat offenders.