A lavish mansion that was once the backdrop to the infamous wedding of disgraced politician Salim Mehajer has been the target of a suspected firebombing.

The four-storey property on Francs Street in Lidcombe, in Sydney’s south-west, was allegedly firebombed at 9.30pm yesterday.

A neighbour called the authorities after hearing the property’s fire alarm blaring, with Fire and Rescue NSW rushing to the scene.

Firefighters have confirmed that the blaze is being treated as suspicious and the investigation is ongoing.

“The responding firefighters have identified some areas of serious concern of how this fire has ignited,” FRNSW Superintendent Adam Dewberry said.

“All our firefighters are trained to identify burn patterns and fire behaviour, they’ve identified areas that aren’t consistent with an accidental fire.”

One resident said they saw a man trying to kick the door to the property down while another said they saw a person dressed in black running from the scene.

The home, which is where Mehajer celebrated his wedding to his now ex-wife by shutting down the entire street, was sold by the bank just two months ago for $3.85 million.

9News understands the new owners of the home were planning to tone back the property and resell it. 

Meanwhile, the former deputy mayor of Auburn is serving time behind bars for fraud and domestic violence offences.

He will be eligible for parole in six months time.