Africa's biggest animals were poached in near record numbers in 2012, with surging demand for horn and ivory from Asia driving the slaughter of rhinos and elephants.

By mid-December, poachers had killed 633 rhinos in South Africa, according to environment ministry figures. That marks a new annual peak in the country that is home to most of the continent's rhinos, and a sharp rise from the record 448 poached last year and the mere handful of deaths recorded a decade ago.

In pictures: The poaching wars

Elsewhere in Africa, the slaughter of elephants continued unabated, with mass killings reported in Cameroon and Democratic Republic of Congo. According to conservation group TRAFFIC, which monitors global trade in animals and plants, the amount of ivory seized will likely drop from 2011, when a record number of big hauls were made globally. But the trend remains grim.

"It looks like 2012 is another bumper year for trade in illegal ivory though it is unlikely to top 2011," said Tom Milliken, who manages TRAFFIC's Elephant Trade Information System.

In 2011, an estimated 40 tonnes of illegal ivory was seized worldwide, representing thousands of dead elephants. So far this year, about 28 tonnes has reportedly been seized but the number is expected to climb as more data comes in.

"The last four years since 2009 are four of our five highest volume years in illegal ivory trade," said Milliken. Demand for ivory as ornamental items is rising fast in Asia, in tandem with growing Chinese influence and investment in Africa, which has opened the door wider for illicit trade in elephants and other animals.

Rhino horn has been used for centuries in Chinese medicine, where it was ground into powder to treat a range of maladies including rheumatism, gout and even possession by devils.

Ivory smuggling has also been linked to conflict, and last week the United Nations Security Council called for an investigation into the alleged involvement in the trade of the Lord's Resistance Army (LRA) in Uganda.

Led by warlord Joseph Kony, who is being hunted by an African Union and US-backed military force, the LRA is accused of terrorising the country's north for over 20 years through the abduction of children to use as fighters and sex slaves.

"The illegal killings of large number of elephants for their ivory are increasingly involving organised crime and in some cases well armed rebel militias," the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) said in a statement this week.

"In Bouba N'Djida National Park, in northern Cameroon, up to 450 elephants were allegedly killed by groups from Chad and the Sudan early this year," said CITES, which is an international agreement that oversees trade in wildlife.

In the case of rhino horn, demand has also been growing in Vietnam, where a newly affluent class has been buying it to treat ailments ranging from hangovers to cancer. The claims have no basis in science but demand has pushed the price of the horn up to $65,000 a kg on the streets of Hanoi, making it more expensive than gold.

Most of the rhino killings take place in South Africa's Kruger National Park. Gangs armed with firearms and night-vision goggles enter from neighbouring Mozambique, from where observers say the horn is often smuggled out through the same routes used to bring illegal drugs from Southeast Asia into Africa.

"Kruger is a national park the size of Israel and it is incredibly difficult to police," said Julian Rademeyer, author of 'Killing for Profit', a book published this year that examines the international rhino horn trade.

"You have very advanced international syndicates run like business operations that are very good at getting horn out of here," he said.

Rademeyer expects the number of rhino killings to rise even higher next year, pushing the population closer to a tipping point that leads to its decline. South Africa has deployed its military to patrol Kruger while its tax agency SARS and police have stepped up the fight. But it also lost ground in 2012 due to a two-month strike by National Park workers and corruption within the ranks of the park service that undermined its anti-poaching efforts.

South Africa hosts virtually the entire population of white rhino - 18,800 head or 93% — and about 40% of Africa's much rarer black rhino. Africa's elephant population varies.

Estimates for the numbers in Botswana are as high as 150,000, but in parts of central and west Africa the animal is highly endangered. "Central Africa has been bleeding ivory but for the last few years there has also been an upsurge in poaching in Kenya, Tanzania and Mozambique," said Milliken. Trade in rhino horn is strictly prohibited under CITES, while that for ivory is mostly illegal.