Customs officials on Wednesday said they had arrested five people on suspicion of selling counterfeit pharmaceutical drugs and cosmetic products in Mong Kok worth around HK$620,000.

The arrestees were suspected to have violated the Trade Descriptions Ordinance.

Those arrested were three men and two women aged between 28 and 90.

An investigator from the Customs and Excise Department, Kenny Chan, said that salespersons, working for a supplier, brought the goods to retailers to sell at low prices.

He said the suspected counterfeit items were found in an operation on Tuesday, when officers searched three retail outlets in Mong Kok and a warehouse in Fo Tan.

The officer said it was difficult for customers to tell the difference between genuine and counterfeit goods.

But he noted that while the packaging and bottles of the suspected counterfeits looked real enough, some of the anti-counterfeiting features were not done in a detailed manner.

"When you compare the real goods to the counterfeit ones, the pattern at the bottom of the bottles is different. It's smooth for the genuine goods and relatively rough for the fakes," Chan said at a press briefing.

"We can also see that the trademarks printed on the genuine goods are clear whereas for the counterfeits they are not."

Chan believed that some of the counterfeit goods had already been sold on the market, but officers had not received any complaints from the public so far, such as the products causing skin rashes or other more serious issues.

He said samples of the goods would be sent to the government laboratory for tests.