A conference on tiger conservation in Nepal has begun with a warning that traders and poachers are better organised than conservationists.
World Bank President Robert Zoellick said that the illegal activities of traders and poachers is estimated to be worth over $10bn annually.
"That is second only to weapons and drug smuggling," Mr Zoellick said.
His warning came as conservationists said that the worldwide population of tigers in the wild is now below 3,500.
Mr Zoellick said that poaching is the most urgent and immediate threat to tigers and that illegal trade in their body parts remains highly profitable in China and other Asian countries.
He argued that the poaching problem has now become so great that supposedly "secure" reserves across Asia have been wiped out while other species - such as Asiatic lions, snow leopards and clouded leopards have also declined significantly.
His comments were backed up by Nepalese Prime Minister Madhav Kumar Nepal and conservationists who said that tigers will become extinct unless the international community unites urgently to find new strategies to ensure their survival.
Mr Nepal told the opening of the conference - attended by 200 delegates from 20 countries - that collective action was needed to address the problem.
"Global and regional solidarity and collective strategies armed with concrete actions are more necessary now than ever," he said.
Tiger hunting is illegal worldwide and the trade in tiger parts is banned under a treaty binding 167 countries, including Nepal.
But endangered species continue to attract huge sums of money in China and elsewhere in Asia, with their body parts used in traditional medicines and aphrodisiacs while their skins are used for furniture and decoration.
Wildlife experts estimate that a single tiger trades for a maximum of about $1,000 in Nepalese markets, but can fetch at least $10,000 internationally.
Experts say that only about 3,200 tigers survive in the wild, down from 100,000 a century ago.