The densely forested central African country is home to about half the world's roughly 100,000 remaining forest elephants, the smallest species of elephant and coveted by ivory dealers for their harder and straighter tusks.
A study conducted by Gabon's government along with advocacy groups WWF and the WildlifeConservation Society found two-thirds of the forest elephants in Minkebe park had been killed off since 2004, or about 11,100.
"If we don't reverse this situation rapidly, the future of elephants in Africawill be compromised," Lee White, executive secretary of Gabon's national parks agency, said in a statement issued by Gabon's presidency.
Demand for ivory for use in jewellery and ornamental items is rising fast in Asia. Conservationists say growing Chinese influence and investment in Africa has opened the door wider for the illicit trade in elephant tusks.
Poachers are often armed with large-calibre rifles and chainsaws to remove tusks, the statement issued by the presidency said. They have secret camps in the rainforest, evading small deployments of park guards and leaving rotting elephant carcasses in their wake.Eco guards patrol the Oua river in north-west Gabon. Rivers are often used as quick ways to export poached ivory and other bush meat out of the jungle. Photograph: James Morgan/WWF
A park official said most of the poachers were believed to be from neighbouring Cameroon, where the government has deployed army helicopters and hundreds of troops to protect its own dwindling elephant population.
Gabon security forces last week arrested at least one gendarme who was transporting tusks in a government vehicle, according to the statement, underlining the risk of corruption in an increasingly lucrative black market trade.
"If we do not want to lose the last elephants in central Africa, the illicit ivory trade needs to be treated as a grave crime that corrupts governments and seriously undermines economic development and security," said Bas Huijbregts, head of WWF's anti-poaching campaign in the region.
Cameroon deployed about 600 troops to its Bouba Njida national park, a former safari tourism destination, late last year to combat horse-mounted Sudanese poachers who killed up to 450 elephants in 2011 and 2012.
In 2011, an estimated 40 tonnes of illegal ivory was seized worldwide, representing thousands of dead elephants. Figures for 2012 are expected to be similar, according to conservation group Traffic.
Ivory smuggling has also been linked to conflict. Last year the UN 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 more than 20 years through the abduction of children to use as fighters and sex slaves.