Mike Friedel, of the department's Code Compliance office, told a local website: "I don't see any non-homeowner certificate that allows them to do short-term rentals.

"If they're doing short-term rentals, it's illegal."

The rule was introduced in the 1980s after local residents complained that visitors staying for short periods were hosting noisy parties and generally disrupting the area.

There is no suggestion that the Obamas have breached any rules by unknowingly staying in the ineligible property, for which they paid up to $6,000 (£3,864) a night. But Mr Weinberg could face a fine of up to $1,000 (£644).

Mr Weinberg's company, Paradise Point Estates, has been keen to exploit the name of its high-profile tenant. Its website describes the property as the "Obama Winter White House".

The "number one presidential vacation destination" offers "classic beachfront elegance at its finest" and is "built for exceptional security, comfort and elegance," it claims.

"The lavish ocean-front estate is fully appointed with exquisite amenities and custom finishes and furnishings from around the world," it adds.

Mr Weinberg, who did not return a request for comment, told local reporters he avoided breaking the law banning short-term rentals by keeping the property empty for the remainder of the 30-day period.

However, local experts have said this commonly-used excuse holds no weight and the law is perfectly clear.

"You will not rent for a period of less than 30 days," a spokesman for Ikaika Anderson, the chairman of the city zoning committee, said. "That's what's in the land-use ordinance".