An Adelaide Mayor will be investigated for using council premises for personal use — because she baked a cake for her son's birthday.

Key points: Heather Holmes-Ross baked a cake for her son's birthday

Heather Holmes-Ross baked a cake for her son's birthday The Mayor will be investigated for using council facilities

The Mayor will be investigated for using council facilities Minister Stephan Knoll says an investigation is a waste of time

Heather Holmes-Ross — who is the Mayor of Mitcham, in Adelaide's inner south — baked the cake in the council's kitchen, posting about it on her work Facebook page last month.

"Work/life balance in action. I made the dessert in the council kitchen between appointments," Ms Holmes-Ross wrote on November 3.

"The smell of melting chocolate permeated through the building making it seem very homely.

"I'm not sure that a mayor has baked in the kitchen before. Happy birthday son."

The original post was accompanied with a photo of her son and the cake, drawing praise from followers.

"I would say that is another first Heather. Mayor bakes birthday cake at work!" one comment read.

"You never cease to amaze me Mayor Heather, so down-to-earth and loving and caring. Happy birthday to your son," another user said.

However, Ms Holmes-Ross later came under fire because of council regulations stating that officials cannot use council facilities for their own benefit.

A Mitcham Council spokeswoman told the ABC that it had received a complaint and there would be an investigation.

The spokeswoman said whether it was an internal or external investigation would be up to Mitcham Council CEO Matthew Pears.

The City of Mitcham also provoked controversy earlier this year after deciding not to host Christmas carols. ( Supplied )

Mayor calls out gender inequality

Ms Holmes-Ross has since taken to Facebook to defend her actions, suggesting there was a gender element to the outcry.

"I have no words," she wrote.

"If a male mayor had managed to bake a cake for his son during a busy day serving his community at council, he'd be a superhero."

That in turn prompted more expressions of support, with one social media user expressing dismay at the "'Bakegate' dilemma at Mitcham Council".

Local Government Minister Stephan Knoll dismissed the need for an external investigation, saying it would be a waste of time.

Ms Holmes-Ross has defended her actions. ( Supplied: Facebook )

"I really think this is something that isn't necessarily worthy of any sort of attention," he said.

"Whether someone makes a cake and where someone makes a cake isn't really a matter for an integrity body."

Local Government Association president Sam Telfer backed that judgment.

"What the Minister said is appropriate, that covers it well," he said.

A Mitcham local shared their frustration into the matter.

"As long as she's doing her job I don't care what she does with the oven in her private time," the caller told ABC Radio Adelaide on Wednesday morning.

"How silly. It says a lot about local government and its priorities."

Earlier this year, the Mitcham Council came under fire for a proposal to downscale its Christmas carols event, before reversing that decision.