Auckland's mayor is excited after spending half an hour with the former mayor of New York.

Len Brown says he discussed city-building philosophies with Michael Bloomberg - the business mogul worth an estimated $50 billion.

Brown is hoping for a partnership to work on transport problems after Bloomberg reportedly expressed interest in helping shape the modernisation of Auckland.

"Michael is one of the richest people in the world and he and his team are showing a specific interest in wanting to work closely with Auckland as a city that is going through transformation," Brown told the Herald on Sunday from Los Angeles.

Brown also expressed hope that Bloomberg, who is known for his charitability, may be willing to donate his services.

"He spends a large part of his fortune on charitable matters and the work he does in sustainable cities is contributed free," Brown said.

"For example, if he were to attach himself formally to Auckland and help us out on one or two key areas, his advice and the advice of his expert staff would not cost us a cent."

A spokesman for Bloomberg's company says there's no deal on the table, and no plan to engage formally either.