Raids have been carried out on two Sydney properties as part of an investigation by the Australian Border Force (ABF) into the importation of 17 undeclared bulletproof vests.

Performance-enhancing drugs, a flick knife, air pistols and illicit tobacco were found and seized by ABF and NSW police during the raids in Ashcroft and Greenacre on Monday.

It's the result of investigations that were launched in mid June, when a man and a woman arrived into Sydney International Airport from Lebanon via Dubai.

The man's baggage contained the 17 undeclared ballistic vests and a black hoodie featuring an Islamic creed known as the Shahada, while two more vest were found in unaccompanied baggage.

Assistant Commissioner Investigations Steve Lancaster said the ABF was ready to protect Australia from organised crime and terrorism.

"As this operation shows, ABF work does not stop at the physical border and those involved in illicit importation can also expect a knock on the door from an ABF investigator," he said in a statement on Thursday.

The maximum penalty associated for importing undeclared ballistic vests is a fine of $170,000.