Landmines kill or maim about 75,000 people a year in former conflict areas from Angola to Cambodia, with high costs limiting how many can be cleared.
Retired British airline pilot Paul Richard demonstrated his Mineburner system at a test range near the South African capital Pretoria on Tuesday. He hopes to test it in the field within six weeks.
The device - with a gas nozzle - was placed first next to an antipersonnel mine and then an antitank mine and ignited by radio control.
The gas flame burnt through the casing of the mines before consuming the plastic explosive, eventually igniting the detonators and producing small explosions.
"Mineburner definitely fills a niche in the humanitarian sector where large antitank mines are planted on bridges, power lines, in cities or villages where you can't use the normal technique of just blowing them up," said Theo van Dyk, research officer for South Africa's state-run CSIR Defencetek, which helped to develop the project.
Mineburner is also safer because it does not require the transport of explosives, he said.
Inventor Richards said new regulations were making it almost impossible for mine-clearance charities to fly explosives into mined areas, where they are placed on top of landmines to detonate them.
The new device is light, reducing air-transport costs, he said.
In countries such as Angola, road and rail infrastructure has collapsed after decades of civil war, with air transport of equipment often the only option.
South Africa's CSIR Defencetek
helped develop the project
"Since 9/11, transporting explosives in a non-military environment has gone from being difficult to more than impossible," he said at the test range.
"In Afghanistan, they have been steaming explosives out of landmines to use them to destroy other landmines. That's very dangerous."
Use of natural gas
Using natural gas - readily available even in countries like Angola where the infrastructure has been destroyed and supplies are difficult to find - is also cheaper, he said.
Richards, who has previously worked on lifejackets and other life-saving devices, said he was giving his services for free.
The private company which will manufacture the product provided some of the components.
Experts typically use explosives
to blow up anti-personnel mines
Mine-clearance charities, United Nations agencies and military and police forces had all expressed interest in the product, he said.
It will cost 75,000 rand ($12,080) for an air compressor, gas tanks and 20 field units. Each reusable field unit will cost 2500 rand.
The first field testing was likely to be in Cyprus against recently found anti-tank mines placed in an urban area with anti-move devices attached, Richards said.
"That could happen within about six weeks," he said. "We are also going into Cambodia in about a week and we are hoping Sri Lanka will ask us to come in."