Online auction site TradeMe is investigating a second user selling chemicals that could potentially be used to make a bomb.
The site on Saturday cancelled the account of a Wellington student who had been selling the chemicals ammonium perchlorate and potassium perchlorate as fertilisers.
The quantities on sale were too small for agricultural use and the chemicals could be used to manufacture explosives, experts said.
But while the site has clamped down on the 65 listings which initially raised eyebrows, a second user selling similar items still has an active account.
The user's five listings did not appear to be suspicious but staff would investigate, TradeMe trust and safety manager Chris Budge said.
"We'll have a look and if we've missed something we'll take the appropriate action and make sure we're consistent, but at this stage it doesn't appear there's any worries with any other members."
Staff would investigate the possibility the two accounts were linked, he said.
TradeMe had initially declined to take action on the first account after seeking advice from the Environmental Risk Management Authority (Erma), which confirmed it was not illegal to sell the chemicals in those quantities.
However, further investigation revealed irregularities with the user's account, including false phone listings.
"It looked like it could perhaps have been a case of identity theft."
Only two people had bid on the listings and there was "no reason" to question the motives of the bidders, Mr Budge said.
"There's no way that we would want knowingly for someone to get harmed through selling dishonest content on the site."
The user's details would be passed on to Erma under a Privacy Act request, and TradeMe would meet with the agency and police this week to discuss further action.
"One option is to put a blanket ban on that particular sort of stuff, or we could maybe have restrictions on the quantity that could be sold if we get that advice," Mr Budge said.
"We certainly don't want to get into the game of looking at every single listing, but there has to be a reasonable methodology which satisfies both the regulatory and the compliance aspects."
Mr Budge warned TradeMe had access to data dating back some time which could be passed on to authorities.
"If you do try to do something illegal, there is a whole bunch of data that's sitting there," he said.
"If someone bought it for an illegal purpose, say to make an explosive, New Zealand police are very good and there will be data there to find out who they are."
Erma said it would consider reviewing its regulations if the need arose, Radio New Zealand reported.
NZPA