Officials are probing how a 51-year-old highway bridge came to collapse in the Italian port city of Genoa yesterday, killing at least 26 people and injuring 16 others as it sent dozens of vehicles tumbling into a heap of concrete and twisted steel.

A new super security agency has been launched to target child sex offenders, following up on Immigration Minister Peter Dutton's pledge to do all in his power to deport pedophiles with dual citizenship.

Mr Dutton's agency will be run by the Office of Home Affairs and aims to crush pedophile syndicates.

"We are working with national police and intelligence authorities now to try and identify some of those people," he said.

Bruce Morcombe has praised the agency as a good step. ()

Since 1949, just 33 citizenships have been torn up by the Australian government.

Of those, 17 cancellations have happened in the past three years, overseen by Mr Dutton.

Since 2014 he has torn up the Australian passports of five people with New Zealand citizenship, three from the United Kingdom, two from Sudan, two from Vietnam, and one each from Canada, South Africa, Ghana, China and the US.

The agency will focus on digital safety. ()Mr Dutton has torn up the passports of 17 people in the past three years. ()

"We are importing these people into our country, we are giving them citizenship and they are abusing that privilege and the government has said enough is enough, this has to stop," advocate Howard Brown said.

"And so this is a step that we all applaud."

Mr Dutton hopes the new approach to speed up investigations will be his lasting legacy.