An Australian law barring child sex offenders from leaving the country took immediate effect on Wednesday (13 December), when it prevented a convicted paedophile from boarding a flight at Sydney Airport.

The man was turned away from the airport under the new sex tourism law.

The new law, which has been described as a "world first", prevents convicted child sex offenders from leaving Australia without permission from law enforcement agencies.

The sex tourism law aims to stop Australian paedophiles from abusing children in developing countries.

There are around 20,000 paedophiles on the Australian National Child Offender Register.

In 2016, 800 offenders travelled overseas, with over half going to South-East Asia, according to Australian Foreign Minister Julie Bishop. Around 40% of those failed to notify the authorities, she said.

Many senators called for a law to prevent what they called "child rape holidays" after a clear pattern emerged of Australian sex offenders travelling overseas to engage in child sex tourism.

"For too long, these predators have traveled overseas undetected, including to countries where weaker laws mean they have opportunities to commit heinous crimes," Bishop told reporters on Wednesday.

"Australia has up to 20,000 registered child sex offenders who have served their sentences, but are subject to reporting obligations that help protect the community," she said.

Justice Minister Michael Keenan described the new legislation as "the strongest crackdown on child sex tourism ever".

"No country has even taken such decisive and strong action to stop its citizens from going overseas, often to vulnerable countries, to abuse kids," he said.