Canberra: Convicted Australian pedophiles will have their passports cancelled and will be banned from travelling overseas under strict new laws designed to stop underage sex tourism.

The laws, unveiled on Tuesday, will be formally introduced to Parliament later this week, and will affect up to 20,000 Australians currently on the National Child Offender Register. In the lead up to forming the new law, Australia's Prime Minister Malcolm Turnbull described convicted child sex offenders who go overseas to engage in "child sex holidays" in southeast Asia as "the worst grubs you can imagine" and a "disgrace to Australia".

According to the new laws, a convicted paedophile registered in the lists of the states and territories, which totals about 20,000 people, cannot leave the country or obtain an Australian passport.

On Tuesday, independent Senator Derryn Hinch, who has been one of the leading figures in the push for harsher penalties for sex offenders and pedophiles, said he was "over the moon" and the new laws would be his lasting legacy from his time in the Senate. Hinch, a former radio host in Melbourne, said more than 700 convicted child sex offenders made an overseas trip in 2016, with about half of those to southeast Asian destinations to engage in "child rape holidays".

The laws are expected to pass Parliament with bipartisan support, and will result in Australia having some of the harsh anti-child sex measures in the world, as the passport bans will be final and will not be open to appeal.

Last year, Australian national Robert Andrew Fiddes Ellis, 70, was sentenced to 15 years in prison for sexually abusing 11 girls, aged seven to 17, over a two-year period in Bali (Indonesia). This legislation is "the strongest crackdown on child-sex tourism ever", said Justice Minister Michael Keenan. "No country has ever taken such decisive and strong action to stop its citizens from going overseas, often to vulnerable countries, to abuse kids," the Minister said.