The international body which named Perth Lord Mayor Lisa Scaffidi the world's second-best mayor in 2012 now says it would not have even considered her for the title given her breaches of ethics.

Ms Scaffidi stepped down from her duties last week to challenge an 18-month ban from office, ordered by the State Administrative Tribunal (SAT), over her failure to disclose gifts and travel.

A founder of the international City Mayors Foundation think-tank which anointed Ms Scaffidi the runner-up in the prestigious World Mayor Prize said it appeared she had breached the competition's code of ethics.

Ms Scaffidi was given the prestigious award behind acclaimed Bilbao mayor Iñaki Azkuna, who commissioned renowned architect Frank Gehry to design a Guggenheim museum which sparked a tourism resurgence in the Spanish port city.

Third-place getter was Indonesian president Joko Widodo, who was then the wildly popular civic leader of Surakarta.

At the time Ms Scaffidi tweeted: "So thrilled! Only woman in top ten! One for the ladies! Thk you all."

But now founder Tann Vom Hove said he and his colleagues were in no doubt she had breached the World Mayor Prize's code of ethics.

"Had we had all the facts back in 2012, we would not have considered her for World Mayor honours," he told the ABC.

"I will discuss with other City Mayors Foundation colleagues what steps we ought to take. I will also ask her lawyers for comments."

Multiple breaches took place prior to award

In awarding her the runner-up prize, the foundation said Ms Scaffidi had "succeeded in raising the city's international profile while at the same time making local bread-and-butter issues her priority".

"She regards social media as the promotional tool of the 21st century and says she communicates through Facebook and Twitter with many citizens which she could not reach by more traditional means."

The World Mayor Prize was established by the foundation in 2004 to celebrate mayors who had made lasting, positive changes to their cities and to promote good, honest local government.

Like all candidates for the 2012 prize, Ms Scaffidi signed up to the foundation's code of ethics, including the pledge that:

"Mayors shall support and uphold the letter and intent of the laws of their cities and nations as well as relevant international laws. They shall demand the same degree of respect for the law from all members of their administrations."

Yet, as she would later admit to the SAT, she had already breached the Local Government Act five times in the years before.

This included failing to properly disclose gifts and travel provided by companies which had a relationship with the City of Perth, including:

A $46,230 trip to the 2008 Beijing Olympics provided by BHP Billiton

A $46,230 trip to the 2008 Beijing Olympics provided by BHP Billiton A 2008 trip to Broome's Cable Beach Club, paid for by property company Hawaiian Investments

A 2008 trip to Broome's Cable Beach Club, paid for by property company Hawaiian Investments A hospitality package at the 2009 Leeuwin Estate concert provided by BHP Billiton

These examples were also investigated by the Corruption and Crime Commission, which in a scathing report said Ms Scaffidi had "failed in her duties" by not disclosing the travel.

Mr Vom Hove said he was aware of the CCC report back in 2015 but had chosen not to take any action.

"We gave the Lord Mayor the benefit of the doubt and decided not to take any actions, particularly as she was re-elected shortly afterwards," he said.

"Obviously, the decision of the State Administrative Tribunal changes the situation."

Mr Vom Hove said he was waiting for a response from Ms Scaffidi and her legal team before taking any action.