Rhinos are being killed in such unprecedented numbers that there are realistic fears they could be wiped from the face of the planet within a generation. If this happens, it will be the first major extinction of an animal in the wild since the worldwide conservation movement began.

The bare statistics are horrifying. In South Africa, more rhinos are being slaughtered for their horns in a single week than were killed in a whole year a decade ago. And the death toll is fast accelerating. In 2007, a mere 13 were killed. In 2008, it was 83, and, a year later, 122. Last year it was 448, and this year, by 19 April, it was 181. That is equivalent to 600 a year in a country which is home to 93 per cent of all white rhinos. One expert thinks that at this rate the species could be wiped out by 2025. Others think it could take longer. Patrick Bergin, chief executive of African Wildlife Foundation, said: "If the poaching of rhino continues at current rates, we could see their extinction within our lifetime. The situation is absolutely at crisis levels."

This attrition is being driven by the astonishing street value for rhino horn, which fetches £40,000 a kilo, more even than gold. Chinese medicine and jewellery are the main markets, but, in recent years, widespread rumours in Vietnam that rhino horn can cure cancer has seen demand there rocket. As a result, the Javan rhino became extinct in that country in November, the last known animal being found dead with its horn hacked off.

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There has also been a huge and sharp rise in elephants being killed for their ivory. Mozambique reports that in just one reserve the number of elephant carcasses found in 2011 is nearly 25 times greater than 10 years before. And the wildlife trade monitoring network Traffic said that 2011 was by far the worst year for ivory seizures since the group's records began more than 20 years ago. The amount of ivory seized last year probably equates to some 2,500 dead elephants, according to Traffic.

Organised crime has moved into both rhino and elephant poaching, with hi-tech equipment used for industrial-scale killing. Reuters reported last week from the Garamba National Park in the Democratic Republic of Congo on a family of elephants killed when poachers swept over them in a helicopter gunship. The report said: "The scene beneath the rotor blades would have been chilling: panicked mothers shielding their young, hair-raising screeches and a mad scramble through the blood-stained bush as bullets rained down from the sky. When the shooting was over, 22 elephants lay dead ... their tusks and genitals removed for sale in Asia."

Richard Emslie, scientific officer for the African rhino group at the International Union for Conservation of Nature, said: "We are facing a horrific situation at the moment where some of the poachers are using veterinary drugs, drugging the rhinos and then hacking off the horns and part of the face at the same time, so they get the whole lot, while the animal is still alive."

So critical is the situation that earlier this month, an emergency summit of wildlife authorities, scientists, owners of private rhino reserves and security experts was hosted in Nairobi by the African Wildlife Foundation and the Kenya Wildlife Service.

A statement issued afterwards said: "The situation is rapidly reaching crisis levels and requires far-reaching efforts to ensure the continued survival of rhinos across Africa ... Africa's rhino population is currently estimated at 25,000 – still low in relation to historical numbers – and it is suggested that, if poaching continues at current rates, there will no longer be any rhino left in the wild by 2025."

Jo Shaw, a Johannesburg-based rhino specialist for Traffic, said: "Very serious levels of organised crime are orchestrating this illegal activity. The people now trading in rhino horn used to be trading in drugs and arms and human trafficking, and probably still are, but they've found this new valuable resource that is less well protected."

Helen Gichohi, president of African Wildlife Foundation, said: "Wildlife authorities, private rhino reserve owners, conservation organisations and others have made valiant efforts to halt the rhino poaching crisis, but these disparate actions have sadly been no match for this epidemic that is plaguing Africa."

As an example of the kind of resources available to crime groups, Ken Maggs, the head of the environmental crimes investigation unit for South African National Parks, said one person who was recently arrested for trade in rhino horn had £401,180 in cash in the boot of his car.

Ben Janse van Rensburg, head of enforcement for the Convention on International Trade in Endangered Species of Wild Fauna and Flora (Cites), the international treaty that governs trade in plants and animals, said: "The biggest challenge is that in the past few years there has been a big shift from ordinary poachers to organised crime groups. They are really, really well resourced and they have significant networks globally. You're dealing with serious transnational organised crime." And their targets are Africa's white and black rhino, a total population estimated by some to be as high as 25,000, but by others to be as low as 11,000.

This month's Kenya summit listed the actions needed to combat the situation; these included increasing the number of anti-poaching units, creating a DNA database of rhinos, using helicopters to track poachers, and establishing tougher laws on poaching and trading in horn. A statement said: "Strong protection forces on the ground are a must. Case studies of Asian rhino protection in certain national parks in Asia have demonstrated that the more trained and properly equipped anti-poaching staff there is in the field, the lower the rates of poaching."

In addition, Cites officials are in talks with authorities in South Africa and Vietnam in an effort to find a solution to the rhino poaching crisis. And Britain is leading a special working group to find ways of tackling the illegal trade. This will report to Cites in July.

Meanwhile, on the ground in Africa, according to the African Wildlife Foundation's Dr Bergin: "There is an arms race going on as to who can first use the latest advanced technologies – the rhino horn poachers or those of us fighting to protect this endangered species. For example, Namibia has been piloting the use of automated drones to monitor large areas for illegal incursions by poachers. In small areas, sonar can actually be used to monitor for incursions, but it is very expensive." So bad has the situation become that South Africa has sent in scores of troops to guard the border of Kruger National Park, and increased the number of rangers from 500 to 650.

These measures are unlikely to be enough on their own. A more militant approach is needed says Damien Mander, a former special forces soldier and the founder of the International Anti-Poaching Foundation in Zimbabwe, which trains rangers in combat skills.

He said: "If we're to save the rhino, we really have no choice other than to employ these kinds of tactics against the poachers. Rangers can no longer function like a bunch of boy scouts in the bush. We're no longer dealing with amateurs here; we're dealing with professional criminals who have access to the latest technology. They've militarised their assault on rhino so we must militarise our response against them."

The stakes could hardly be higher. Dr Emslie, of IUCN, said: "In terms of African rhinos, we've lost one and almost lost another of the six subspecies that existed when I was born. Just recently, the Javan rhino subspecies in Vietnam was poached to extinction; the Javan rhino is reduced to 44. There are probably only 150 to 200 Sumatran rhinos – poaching threatens them, too. If the illegal demand continues to increase and prices remain high, then it's a severe threat, not just to rhinos in Africa but all the world's five species."

Mr Janse van Rensburg of Cites said: "If the world's enforcement authorities cannot stop this increasing trend, rhino population growth will not be sustained and we could see populations in Southern Africa decline to highly endangered status in a very short time, which will be a tragedy in terms of conservation and for the rhino."

There are very few wildlife specialists who are optimistic. The conservationist Ian Craig, who helped to found Lewa Wildlife Conservancy in Kenya, said: "The current surge in poaching of rhino, and more recently elephant, across Africa, led by demand from the Far East is essentially just starting. I expect that the worst may yet still be to come."