The Johannesburg city council says an operation in Fourways led to the discovery of almost R9-million in lost revenue due to illegal connections to services since 2015.

"The three properties which were visited were also found not to have complied with the city's bylaws and were fined," it said of the 'Buya Mthetho' sting.

"At some of the properties it was established that water and sewer accounts were not registered with the city and therefore not billed for the last three years."

The operation was led by Buya Mthetho director Lufuno Mashau, the city’s chief operating officer Floyd Brink under the directive of the member of the mayoral committee for finance Funzela Ngobeni.

"During the operation, it was also found that one of the properties did not have an occupation certificate," Ngobeni said.

"Despite residents occupying the 300-unit property, an occupation certificate was never issued at the said property, meaning residents are living in this property illegally. Furthermore, this means the property is not correctly evaluated by the City without an occupation certificate."

The city issued a 14 days notice for the property owners to comply.

"Non-compliance is of great concern in the city, especially since some properties go without being billed for years. Through Operation Buya Mthetho, the City will make every attempt to recover what we have lost during the development of these three properties," said Ngobeni.

The operation will continue carrying out such inspections in order to reclaim the city's revenue.