Canberra, May 30 (IANS): 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, Xinhua news agency reported.

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".

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".

"This will be the greatest thing I could achieve in my first year in the Senate," Hinch said on Tuesday.

"I could have been on (local Australian radio) for years banging away about this, but being elected to the Senate made it possible.

"It is unconscionable behaviour and we are going to stop it."

Meanwhile, Hinch said he received overwhelming support from the government in forming the plans despite some outside complaints that the laws violate "civil rights".

"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," he said.

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.