The search at the Merrylands home is part of a planned police operation, and follows a raid last week in which a semi-automatic firearm was allegedly seized at the property.

"A search warrant relates to ongoing investigations by the State Crime Command's firearm squad and no further information is available at this time," a NSW Police Media spokeswoman said.

Last Tuesday, the home was raided as part of a co-ordinated operation targeting an alleged syndicate smuggling drugs and cigarettes into Australia.

Coined Operation Veyda, the sting was one of the most significant targeting organised crime in Australian history.

The co-ordinated raids on 28 Sydney properties led to the arrests of Michael and Fadi Ibrahim, the brothers of Kings Cross identity John Ibrahim, and Sydney underworld figures Steven Fawaz Elmir, Haykan Arif and Mustapha Dib.

It is understood Wednesday's search operation at the Merrylands home is in no way linked to Operation Veyda, but is part of a separate inquiry by the firearms squad.

In his recently published autobiography The King of the Cross, John Ibrahim reflected on the fibro housing commission Merrylands home where he and his brothers grew up.

With money no object in 2000, Mr Ibrahim bought his mother a clifftop mansion in Dover Heights, in Sydney's eastern suburbs.

However, he wrote that he soon learnt that his mother was "uncomfortable being so close to a cliff and all that wind, and hates being away from the Merrylands home she raised us in".

The nightclub identity later bought the old fibro house, knocked it down and built a two-storey, five-bedroom mansion; the property that was being searched on Wednesday.