Chinese-backed crime groups are leading a surge in African elephant poaching to meet China's thirst for ivory, and terror groups are elbowing in on the lucrative trade, US lawmakers heard Thursday.

Seizures of contraband ivory in Africa and China have soared in recent years as syndicates with deep roots in the billion-dollar wildlife smuggling trade seek to feed the spike in demand among increasingly wealthy Chinese.

The resulting killings -- highlighted by the mass slaughter of elephants in Cameroon, where park officials say at least 480 have been killed by poachers since January -- are putting the pachyderms at unprecedented risk.

"The Chinese government and others have made substantial seizures, but clearly more needs to be done to eliminate the illegal marketplace," Senator John Kerry told a hearing on the global implications of poaching.

"Increasingly, criminal gangs and militias are wiping out entire herds and killing anyone who gets in their way."

Save the Elephants founder Iain Douglas-Hamilton, who has studied elephants in Africa since the 1960s, warned of an "acute crisis" going unnoticed by the wider world, and stressed that China has emerged as "the leading driver of illegal trade in ivory."

He cited Kenyan reports that 90 percent of ivory seized at the country's airports is linked to the Chinese, and that large numbers of Chinese nationals for the first time are "living in Africa, collecting ivory and shipping it out."

Controls imposed to restrict ivory imports have "failed," in large part because two one-off sales of legal ivory stocks in South Africa, Botswana and Namibia allowed poachers to exploit confusion over the rules and sell illegal ivory as though it were legal, Douglas-Hamilton added.

Crime syndicates are also exploiting lax US rules on shell companies that allow foreign nationals to set up vast money-laundering operations, said Tom Cardamone, managing director of monitor group Global Financial Integrity.

GFI said the ivory trade has become a lucrative offshoot of the illicit wildlife trade, valued at up to $10 billion.

Cardamone said US authorities and others must tighten corporate rules to prevent crime syndicates and terror groups from "posing serious national security concerns for the United States and our partners."

Senator Chris Coons warned of the harmful secondary effects of the ivory trade.

"It is financing terrorism, guerrillas and organized crime," Coons told AFP.

"We should add the trafficking in illegal ivory to counterfeiting, to counternarcotics and terrorism, as among the central issues that we're pushing with countries in international fora."

Experts have described 2011 as an "annus horribilis" for elephants, with the seizure of more than 23 tonnes of illegal ivory last year -- tusks from nearly 2,500 animals.