Police say they have broken up a Middle Eastern crime gang that was once linked to the 1997 murder of police officer David Carty.

Heavily armed police have raided properties across south-west Sydney as part of an investigation into alleged members of Dlasthr (The Last Hour).

Officers carried out surprise hits on houses at Green Valley, Prairiewood and Fairfield, taking three people into custody.

They have been charged with directing or participating in a criminal group and supplying drugs.

Police have confirmed the raids were part of a two-year investigation by Strike Force Evesson which saw 15 members of Dlasthr arrested and charged with a range of offences, from drug supply to grievous bodily harm, last September.

Strike Force Evesson was set up to target criminal activities by Dlasthr bringing gang members before the courts and disrupting their criminal activities.

Superintendent Peter Lennon says it is the end of a long investigation into the gang and he is confident the group has been dismantled.

"However, I would warn anybody that we will recommence any investigations that we need to in Fairfield or any other area to investigate drug supply, kidnapping or public place shootings which was the responsibility of Evesson when it first started off," he said.

Last year, the then police minister Mike Gallacher told New South Wales Parliament that Dlasthr is a violent, organised gang that has been involved in public-place shootings, vicious assaults, drug dealing and extortion.

The group is said to have originated from another gang, called the Assyrian Kings.

The Assyrian Kings were implicated in the murder of off-duty police officer David Carty in 1997.

Constable Carty, 25, was stabbed in the heart and stomped on in the carpark of the Cambridge Tavern in Fairfield.