A Sydney family allegedly ran an expansive crime empire that stole and illegally exported thousands of tins of baby formula to China.

Police today said they had arrested six people - including four from the same family - over the alleged co-ordinated theft of more than 4000 tins of baby formula, Manuka honey and other goods.

The syndicate - allegedly headed by a 48-year-old woman - handled more than $1 million of stolen goods in the past year and may have run their empire over a number of years.

The man detained by police after arriving at Sydney Airport from China. (Supplied)

"We're thinking this was quite an expansive criminal group that was exploiting an overseas market at the disadvantage of the Australian public," Detective Superintendent Danny Doherty said.

"It is quite lucrative.

"The reasons are quite simple - it's greed and the exploitation of a market overseas for the benefit of a criminal organised group."

Some of the 4000 tins of baby formula found during a police raid last year. (Supplied)

The gang allegedly used a network of thieves who delivered the goods back to locations in Carlingford before it was sold overseas.

Police say critical information from "all the major retailers" helped investigators follow the trail back to the crime syndicate.

The alleged leader was arrested in August but police only went public with key details once they picked up a 31-year-old man on Saturday at Sydney Airport after he arrived from China.

"Considering members of his family had already been arrested and charged, it probably was something he may have expected, but he didn't expect it to happen at the airport when he got off the plane," Det. Supt Doherty said.

Cash recovered during the police operation. (Supplied)

Three men, aged between 35 and 53, and a 29-year-old woman have also been arrested.

Police believe more than a dozen people were involved.