The suspects included a 34-year-old Chinese woman and two 35-year-old Chinese men.
They had arrived at the Bandaranaike International Airport on China Eastern Airlines flight MU-6017 from Shanghai at around 6.43 p.m. on May 19.
Customs officers said the suspects attempted to pass through the “Green Channel” at the arrival terminal, which is designated for passengers with nothing to declare.
During inspections, officers became suspicious of a black polythene bag carried by one of the male passengers among several duty-free shopping bags. A search revealed part of the stock of mobile phones concealed among toffees and chocolates.
The seized mobile phones and batteries are estimated to be worth around Rs. 514,000.
Customs officers are taking steps to detain the suspects and hand them over to the relevant police authorities for further investigations.
