Irish based Asians are importing increasing quantities of illegal "health supplements" into this country by post from China, the Revenue Commissioners have said.
Typically used in body building, the supplements are then distributed around the country.
Separately, customs officers at postal depots also observed a large increase in the number of detections of Viagra type medicines which were illegally imported last year.
According to Michael Colgan, who is in charge of Revenue's central intelligence and drugs co-ordination, these appear to have been ordered over the internet and are sent from India.
He added that there is also evidence of steroid smuggling from eastern Europe, resulting in a number of detections in this area.
Amid ongoing concern about the potential for individuals to order real or counterfeit drugs either online, or to self-medicate with drugs bought from illegal distributors based in Ireland, Revenue figures reveal that by the middle of December there were over 330 seizures of medicinal drugs by customs officers last year.
The seizures included prescription medicines such as the anti-anxiety drug Diazepam, the sleeping pill Zopiclone and steroids.
Overall, they consisted of some 532kg worth of drugs, as well as 202,054 tablets where volumes are not available.
Mr Colgan said the majority of seizures have been made in the postal system from countries such as China, Pakistan, India and Thailand. There have also been a number of large seizures at Dublin airport, in freight and passenger baggage.
"People are importing in big numbers, thousands of pills at a time, but you cannot import them legally unless you are one of the licence holders," he told the The Irish Times. "They are often prescription drugs or purport to be prescription drugs . . . but who knows what is in them?"
Once seized such packages are sent for analysis to determine their contents. Revenue and the Irish Medicines Board work together to combat this type of illegal activity, he said.
For its part, the board has in the past sought to close down Irish-registered websites selling prescription-only medicines. Last year it closed about a dozen sites but can only pursue those registered in Ireland.
"Where detections have been made in passenger baggage the goods have been primarily steroids, Diazepam and Zopiclone," Mr Colgan said. "The majority of steroid and Diazepam couriers have been of Pakistan origin on flights originating in India or Pakistan."
"In one seizure in 2007, a total of 76kg of steroids was detected which resulted in the arrest and charging of three Pakistani nationals. This case is currently before the courts."
However, Mr Colgan said couriers of Zopiclone have tended to be Irish nationals en route from Spain to Ireland. Quantities of up to 15kg have been detected with individual couriers.
In addition, there have been seizures of large shipments of so-called "health supplements" in air freight from China. Investigations are ongoing into this.
"Asian individuals are buying it from their home countries and then it is sent here in bulk and distributed throughout Ireland."