The world's biggest conference on the international wildlife trade got underway Saturday in Johannesburg, but African countries lashed out at Western charities for "dictating" how they should protect their elephants.

Over the next 12 days thousands of conservationists and top government officials will thrash out international trade regulations aimed at protecting different species.

A booming illegal wildlife trade has put huge pressure on an existing treaty signed by more than 180 countries -- the Convention on International Trade in Endangered Species (CITES).

And the plight of Africa's elephants, targeted for their tusks, generated fierce debate as the talks kicked off.

A recent census showed a 30 percent decline in the savannah elephant population over seven years, and new data released by wildlife monitor TRAFFIC on Saturday showed a "rising trend in large raw ivory shipments" in 2015.

The new data underlines "the crucial need for renewed efforts by governments meeting this week at CITES who need to redouble their efforts to bring the illegal ivory trade firmly under control," said Steven Broad, TRAFFIC's executive director.

Ginette Hemley, who is heading the WWF delegation to the talks, described the data as "extremely worrying".

But four countries -- Zimbabwe, Zambia, South Africa and Namibia -- castigated Western-based animal charities, saying they "dictated" on how African resources should be managed.

"Please leave us alone, don't just come and dictate what we should be doing," Zambian Tourism Minister Stephen Mwansa told a news conference.

Fortune Charumbira, head of Zimbabwe's traditional chiefs, blasted "elitist NGOs who are coming from countries where there are no animals", describing them as "domineering".

A coalition of 29 African countries is pressing for a total halt to the ivory trade to curb poaching of elephants, but other delegates believe it would only fuel illegal trading.

- Insatiable demand -

CITES forbids trade in elephant ivory, but Namibia and Zimbabwe have made a proposal asking for permission to sell off stockpiles to raise funds for local communities that co-exist with the animals.

The European Union said it "will support a continuation of the ban on international trade in ivory and press for the adoption of strong measures against ivory trafficking, as well as trafficking affecting rhinoceroses, tigers, great apes, pangolins and rosewood."

Illegal trade in wildlife is valued at around $20 billion (18 billion euros) a year, according to CITES.

South African President Jacob Zuma opened the talks with a warning of the dire consequences of failing to tackle the demand for elephant ivory, rhino horn and hundreds of other endangered wild animals and plants.

"Levels of exploitation of some animal and plant species are high and the trade is capable of heavily depleting their populations and even bringing some species close to extinction," Zuma said.

CITES' secretary general John Scanlon said the meeting would "review trade controls of close to 500 species of wild animals and plants", including the rhino, the pangolin and the silky shark.

And while Scanlon hailed the deep commitment of all those taking part, he warned that "they sometimes have differing views on the best way to achieve this".

CITES banned trade in rhino horns 40 years ago, but prohibition has not reduced illicit hunting, which has seen a recent boom in South Africa.

Around 5,000 white rhino -- a quarter of the population -- have been slaughtered over the past eight years, with the majority killed in South Africa, home to 80 percent of the world's rhino.

Rhino poaching is driven by insatiable demand in Vietnam and China for the horn, which is mistakenly believed to have medicinal powers curing everything from hangovers to cancer.

But China is now taking steps to clamp down on domestic demand for ivory.

"China has made significant moves to combat illegal trade in wildlife," Scanlon told reporters, adding it had started prosecuting people involved in illegal trade and closing down local retail markets.

But he warned that illegal wildlife trafficking was "occurring on an industrial scale, driven by transnational organised criminal groups".