A three-month investigation into a sophisticated cigarette smuggling ring by Shanghai police has resulted in the arrest of 20 suspects and seizure of 4,000 cartons of cigarettes.

Shanghai customs reported that four suspects from Japan arrived at Shanghai Pudong International Airport last Saturday. With the help of a Chinese ground crew from an unnamed Chinese airline, the suspects avoided customs agents before being arrested in the airport parking garage with 800 cartons of cigarettes. Police made a number of arrests relating to the remainder of the smuggling ring later that night.

Authorities did not comment on the value of the smuggled cigarettes; but, the Shanghai Daily estimated their total worth, which included such international brands as Seven Star, Marlboro and Peace, to be about 800,000 yuan (US$122,000).

Authorities became aware of the smuggling activity after nine of the alleged smugglers flight history showed they had traveled between Osaka and Shanghai three or four times in a single week, often making the return trip the same day.

Furthermore, four of the smugglers had already received administrative penalties between January and March 2016 for exceeding the limit placed on foreign cigarettes allowed into China. Many of the smugglers were described as being under the age of 26, with some under the age of 21.

The smuggling ring operated in two ways: 1) the suspects’ luggage was redirected to the domestic baggage claim instead of international, thereby lowering scrutiny; or 2) suspects were transferred to the hall for passengers transferring between international and domestic flights when customs officers were not on duty. Both methods depended on “inside” help from airport employees.

The smuggled cigarettes were thought to be destined for the black market in Liaoning Province.

Taxes on cigarettes sold in China doubled to 11 percent last May, and is credited for the country’s slight decrease in cigarette sales. However, as Chinese cigarettes are still considered to be among the cheapest in the world, anti-smoking advocates are pushing to further increase tobacco taxes.