A "lucrative" organised crime ring that allegedly sold baby formula stolen from around Sydney on the black market overseas raked in $1 million in just 12 months, police say.

Key points: A 31-year-old man was arrested after a returning to Sydney on a flight from China

A 31-year-old man was arrested after a returning to Sydney on a flight from China Six more people were arrested in connection to the thefts

Six more people were arrested in connection to the thefts Investigations into black market baby formula were ongoing

Six people have been charged after police received information about coordinated thefts of formula and vitamins from major retailers last year.

Detective Superintendent Daniel Doherty said the "unscrupulous activity" was fuelled by greed and had been operating for years.

"Police will continue to pursue these people because not only are they making a quick dollar out of greed and disadvantaging the mums and dads of Australia, they're also literally taking baby formula out of the mouths of babies," he said.

"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 Doherty said thousands of shipments of formula were sent to China over "a number of years", however the $1 million related to the past 12 months.

Boxes of baby formula seized from Carlingford. ( Supplied: NSW Police )

Australian Border Force (ABF) officers arrested a 31-year-old Carlingford man after he arrived at Sydney International Airport on a flight from China at about 10:30am on Saturday.

Officers searched the man's luggage before arresting and charging him with two offences, including recklessly dealing with the proceeds of crime.

He was granted conditional bail at Parramatta Bail Court yesterday and is due to appear in court again on January 30.

The arrest came about five months after police raided a Carlingford home and allegedly found 4,000 tins of baby formula, vitamins, manuka honey and more than $250,000 of cash.

A 48-year old woman was arrested in connection with the search.

Police continued to track the syndicate's activities and also arrested a 29-year-old woman and three men, aged 35, 53 and 42.

Detective Superintendent Doherty described the investigation as "meticulous" and was "very confident" of further arrests in the near future.

He credited major retailers for providing crucial information that helped track the syndicate's alleged activities.