Nearly 700 rhinos have been killed in South Africa in 2013, making it the bloodiest year yet for rhino poaching.

Last year, a record 668 rhinos were poached for their horns, but that figure has already been eclipsed with the deaths of 688 rhinos with three months left of the year, figures from the South African government show. There are around 18,000 white and 4,000 black rhinos in the country.

The dramatic growth in rhino poaching in South Africa, up from just 13 in 2007, has largely been driven by demand in Asia, in particular Vietnam, where rhino horn is seen as a status symbol. A survey of 720 people in Hanoi and Ho Chi Minh City, published earlier this month, found that typical buyers were "educated, successful and powerful individuals" and use rhino horn as currency in networking.

Anti-poaching efforts are turning to technology, such as drones, as well as attempting to elevate the problem from a conservation to a national security issue. In the next fortnight, the US will crush its 6m tonne stockpile of seized ivory in a symbolic act of destruction to raise awareness of the problem.

Edna Molewa, South Africa's minister of water and environmental affairs, told an anti-poaching street parade on Sunday that the trade was also a threat to the country's tourism industry. "Because of the increase in rhino poaching since 2008, rhinos have been at the centre of the world's attention. This is because losing a rhino not only disturbs the ecological balance, but also harms the South African economy through the resulting harm it does to the tourism industry as a job creator, and poses a security threat as international poaching syndicates cross illegally into South Africa to rob this precious animal of its horn," she said.

Heather Sohl, WWF-UK's chief species adviser, said of the latest figures: "The scale of poaching we are now seeing is extremely worrying. 618 rhinos in South Africa have already been killed by poachers in 2013, so it's appalling to think how many may be lost to this illicit trade by the end of the year. Governments need to act with pace and in a way that fits the seriousness of the crime – this is no longer just an environment issue; illegal wildlife trade transcends national boundaries and undermines national security and economic development in some of the world's poorest countries."

Governments and the WWF will meet at the UN headquarters in New York on Thursday to discuss efforts to tackle the problem.