The locks were being changed at the Sturt Street business on Wednesday afternoon, with worried customers streaming in and out enquiring about their properties.

Signs stuck to the office windows indicate the agency is now under the administration of agent Ross Hamilton, who the notice says will be in contact with all existing customers.

Hayden Real Estate was one of Ballarat's oldest real estate agencies.

The business was founded by Basil Hayden in 1928.

John Hayden ran the business for decades before he handed the reins to his son Richard in 1996.

Richard and his wife Lisa Hayden were co-owners of the agency.

Lisa Hayden, a philanthropist, writer and passionate cancer campaigner passed away in January this year after a long battle with breast cancer.

A spokesperson for Consumer Affairs Victoria said it was investigating the "sudden closure" of Skyline Developments Proprietary Limited, trading as Hayden Real Estate Ballarat.

"The Minister for Consumer Affairs, Gaming and Liquor Regulation, Marlene Kairouz appointed Ross Hamilton on 12 March 2019 as a statutory manager under section 89(2) of the Estate Agents Act 1980(Vic) on advice from the Director of Consumer Affairs Victoria and Secretary to the Department of Justice and Community Safety," the spokesperson said.

"The Victorian Property Fund provides compensation to consumers who have lost money due to the actions of an estate agent."

Urgent business enquiries are to be directed to Consumer Affairs Victoria on 1300 55 81 81.

Have you signed up to The Courier's variety of news emails? You can register below and make sure you are up to date with everything that's happening in Ballarat.