TEN headshops that previously sold a range of the legal highs which were banned three months ago remain open across Ireland as garda preparations are underway to incinerate several tonnes of the now illegal, seized drugs.

The 10 stores, two of which are located in Dublin, are selling various drugs paraphernalia including pipes and bongs but are expected to close down soon. There were previously 102 head shops operating in Ireland, and several were making tens of thousands of euro each week. All of the head shops have complied with the law, which has made it a criminal offence to sell all psychotropic substances, and all have been removed from the stores.

Gardaí will continue visit these stores in uniform as well as in covert operations posing as customers enquiring if it is still possible to buy the now illegal substances. If a shop is caught selling these products, it faces prosecution and its owner a jail term of up to five years.

On 12 May, gardaí seized more than five tonnes of drugs from eight "production factories" manufacturing a range of former legal highs. The massive haul, worth tens of millions of euro, was seized by gardaí in a series of raids of factories in Dublin and Cork.

Only a small proportion of the drugs was seized from the country's 102 head shops. The majority were handed over voluntarily when detectives from the Garda National Drugs Unit, supported by local units, visited eight production factories where many of the people involved in the sale and supply of legal highs were manufacturing the products.

One of these factories was in Dublin's Baldonnell and run by Englishmen. Another was in Harold's Cross, while another was operating in Tallaght under the direction of an Australian.

A Polish national was running another one of the premises in Dublin and all of his products were being exported to Poland. Another factory was in Cork and largely served the market in the south.

Before a range of legal highs were banned on 11 May, those involved in the trade were importing the products from abroad and then using premises as "distribution factories" to sort the drugs into thousands of "separate deals".

Many of these premises then turned into "wholesale manufacturing factories", according to a source. When gardaí visited the eight premises, they found people using mixing agents to produce a range of legal highs. In one of the raids, gardaí discovered the floor covered with imitation cannabis leaves that were being sprayed with a substance by people wearing protective masks. A further ban in August outlawed all remaining legal highs.