The wild population of Africa's Northern White Rhino could die out in six months unless poaching is stopped, a London conference has heard.
There are only a handful of rhinos left in the Garamba National Park
The event, organised by the UK Rhino Group at London Zoo, was told that the Garamba National Park in Congo is the animal's only natural habitat.
White Rhino numbers dropped from 490 in 1978 to 15 in 1983 before a conservation scheme to save them began.
Numbers rose but poaching has kept their population small.
Rhinos are normally killed for their horns, which are prized for their medicinal qualities and can fetch large sums on the black market.
Conservationists at the Garamba National Park say poaching there is linked to the war in neighbouring Sudan and has recently become more systematic.
Heavily armed gangs entered the park in April 2004 and an attack in May left two park rangers dead.
Park officials are concerned that the latest offensive is the start of a systematic operation to wipe out the park's rhino and elephant populations.
The poachers have been using trains of donkeys to carry their wares back to Sudan.
There were 30 rhinos in the park in April 2003 but officials believe at least six have been killed since then, with only four born.
The park is managed by a staff of 230 of the Institut Congolais pour la Conservation de la Nature supported by the Garamba National Park Project, which is linked with the International Rhino Foundation.
Nick Lindsay of the rhino conservation team at the Zoological Society of London said that increased funding was vital to stop the new wave of poachers.
He told BBC News Online: "They need funding to increase the rangers. They need more helicopters, more weapons, more cars and more people who are trained to get out into the field.
"If poachers know there is an effective force on the ground this would certainly curtail their operation."
The endangered species
Javan Rhinos: Fewer than 60 wild in Vietnam and Indonesia
Sumatran Rhinos: Fewer than 300 wild in south-east Asia
Indian Rhinos: Around 2,400 wild in India and Nepal
Black Rhinos: Around 3,100 in Africa
Southern White Rhinos: Around 11,000 in Africa
Northern White Rhinos: Around 30 wild in Africa
Mr Lindsay explained that an immediate injection of cash could bring instant rewards by increasing the number of helicopters and cars available to rangers.
"Longer-term it is about getting more people involved, but there is stuff they can do tomorrow."
He added that there is a small herd of the rhinos in a zoo in the Czech Republic and a tiny number of males in San Diego Zoo, but that the population in Garamba needed to be protected to ensure the species survives.
"They continue to breed despite all the problems they face. If the poaching stops, there is a healthy genetic population."
The UK Rhino Group describes itself as "an informal forum for the discussion of rhino conservation issues" and brings together the UK's more than 20 rhino charities.
Its Rhino Mayday event aims to draw attention to the problems of rhino conservation and draws international speakers.