"There have been years without any real action on the ground when it comes to controlling the illegal ivory market," said Oeystein Stoerkersen, chairman of CITES's governing body.
The Convention on International Trade in Endangered Species of Wild Fauna and Flora has set Thailand an August 2015 deadline to fall into line or risk wide-ranging sanctions.
Bangkok is under additional pressure to report back by January on steps to bolster recent laws on registering ivory importers, traders and legal stockpiles, that CITES claims are insufficient.
"Without that, Thailand will face a ban, and a suspension of all trade no matter what commodity it is, of the 35,000 species listed with CITES," he told reporters.
A ban would prevent the country trading anything appearing on that list with another country, including orchids and exotic wood, which are significant export products for Thailand.
"I think that is a strong signal," said Stoerkersen, adding that Thai diplomats at the talks had acknowledged that their country needed to do more.