Four men have been arrested during dawn raids across Sydney's south west as part of a major police investigation into a network of taxi drivers who have allegedly been doubling as mobile cocaine dealers.

Police claim that, under the cloak of routine taxi work, a syndicate of cabbies has been operating a "cocaine delivery service" to hundreds of homes and the doorsteps of some of Sydney's most popular pubs and nightspots.

One of the guns found during Strikeforce Illinois. Credit:Police Media Unit

Following a four-month surveillance operation, more than 100 police from the Central Metropolitan region, Tactical Operations Unit, Riot Squad and South West Metropolitan Region Enforcement Squad swooped on five addresses in Auburn, South Granville and Guildford shortly after 6am on Friday.

Search warrants were executed at the locations and four cab drivers taken into custody. Police says they found drugs, large amounts of cash and firearms.