Convicted paedophiles in Australia will have their passports cancelled to prevent them travelling overseas to offend again under tough new laws which the country hailed as a "world first".
Legislation will be introduced to parliament this month making it illegal for registered offenders to leave or attempt to leave the country as part of a crackdown on child-sex tourism.
"The new laws will prohibit registered child sex offenders from leaving Australia or holding Australian passports," Foreign Minister Julie Bishop said.
"Last year alone, almost 800 registered child sex offenders travelled overseas from Australia."
She said many of them - who often go to developing countries in Asia - were in breach of obligations to notify police that they were travelling, with half of them considered as having medium-high or very-high risk of reoffending.
The move follows several recent high-profile cases of child exploitation overseas, including by Australian Robert Ellis who was convicted last year of sexually abusing 11 Indonesian girls on the resort island of Bali.
Justice Minister Michael Keenan said the new laws were "the strongest crackdown on child-sex tourism ever".
"No country has ever taken such decisive and strong action to stop its citizens from going overseas, often to vulnerable countries, to abuse kids. So this is absolutely a world first," he said.
Mr Keenan estimated the government would deny passports to around 20,000 people who have served their sentences but were still monitored under the Australian National Child Offender Register.
Some 2,500 new cases were expected to be added every year.
Senator Derryn Hinch, who has long campaigned for the measures, said he was "over the moon".
"People say what about their civil rights? Well when you rape a child, you lose some of your civil rights, from my point of view."