Police visited Dunedin K2 retailers last week "and appealed for them to take it off the market", Sergeant Chris McLellan said.
"We realise the dairies are selling a product that is profitable for them, but the reason we are asking them to take the product off the market is all the flow-on health effects ..."
These included users becoming highly aggressive, and experiencing anxiety and hallucinations. The product was also believed to be a "driver of crime".
"People on the substance are doing things that they would not normally do at other times."
The product had appeared for sale in K2-only "tinny houses", two of which had been detected in Balclutha and one in Dunedin, he said.
During the weekend, Dunedin police dealt with three youths who had taken K2 and become aggressive and hallucinated.
"[K2] seems to have become quite popular ... Interestingly, I spoke to some cannabis users who tried it and said they would never touch it again."
Retailers, some of whom had been targeted in synthetic cannabis-related crime, had given a mixed reaction about removing the over-18 product. Some said they would continue to sell K2 until it was declared illegal.
Unlike previous synthetic cannabis products- many of which were banned last year - K2 was often bought in bulk over the internet and divided up into smaller amounts for retail.
Last year, police targeted Kronic retailers in the Dunedin area.
Police introduced controlled purchase operations last year, and set up a working group involving high schools, justice and health officials. The group had now turned its attention to K2.
"When we started with Kronic, we felt the product was bad ... but K2 has taken it to a whole new level."
Sgt McLellan was interested in talking to anybody who was concerned about K2, particularly any report of youths obtaining the product, or of shops selling it "under the counter".
K2 was being tested by health officials, and could join the 28 substances placed under temporary class drug notices, which has led to the removal of 50 synthetic cannabis products from the New Zealand market.
