All but 15 of the world's 195 countries have discussed how to better protect the world's vulnerable species at a wildlife conference in Geneva.

The World Wildlife Conference on Trade in Endangered Species, known as CITES, takes place every three years.

"Business as usual is no longer an option," Ivonne Higuero, Secretary-General of CITES said on the conference's opening day on Saturday.

"The rate of wildlife extinction is accelerating with experts affirming that up to one million species are now threatened," she added.

One of the most popular animals remains endangered; there are about 400,000 elephants left in the wild but poachers kill between 20,000-30,000 each year.

Markets in Asia buy a lot of ivory and some African states with large elephant populations such as Namibia and Zimbabwe are keen to sell their stockpiles of it.

One charity, the International Fund for Animal Welfare, or IFAW, is concerned that there might be more sales of stockpiled ivory.

"We saw the last sale back in 2008, and the following decade we've lost a hundred thousand savanna elephants, 60% of the forest elephants in Africa, following that stockpile sale," IFAW's International Policy Director Matthew Collis said.

"And this has primarily been because these legal markets have opened up avenues for criminals to traffic illegal ivory into those markets and sell it," he added.

The conference ends on August 28, with key decisions expected to be finalised in the last two days.

The gathering followed three months after the first comprehensive UN report on biodiversity warned that extinction is looming for over 1 million species of plants and animals.

It also comes just days after the Trump administration announced plans to water down the US Endangered Species Act — a message that could echo among attendees at the CITES conference, even if the US move is more about domestic policy than international trade.

CITES bans trade in some products entirely, while permitting international trade in other species provided it doesn't hurt their numbers in the wild.

United Nations Environment Programme (UNEP) Executive Director Inger Anderson reaffirmed that "regulated and sustainable trade works."

She mentioned crocodiles as an example, saying that as a result of regulation, "the illegal trade has all but vanished and crocodiles are far more abundant than they were 50 years ago."

The meeting's agenda contains 56 proposals to change — mostly strengthen — the level of protection among vulnerable or endangered species.

But some argue that protections should be downgraded because the relevant populations have stabilised or even increased.

Officials say the decisions are to be based on science, not political or other considerations.