Official figures say 14,000 anti-personnel mines have remained uncleared on the islands since the 1982 war, though some estimates have put the figure at nearer 40,000.
They are creating a major headache for Whitehall officials because Britain does not have the technology to clear them. Under the Ottawa Treaty, due to be ratified by MPs in the autumn, the UK will have 10 years to complete the work.
Attempts during the 1980s to develop equipment capable of detecting and clearing the mines were abandoned when it became clear that 100 per cent effectiveness could not be guaranteed. Islanders said they did not want to risk mine-clearers' lives in clearance operations when even a 1 per cent failure rate would mean they still could not use their land. Twenty square kilometres of beach and former farmland are out of bounds to islanders.
The problem is that the mines are plastic, and fiendishly difficult to detect. They are also buried in shingle and peaty soil which moves around and which makes using vehicles for the work very difficult.
A spokesman for the Ministry of Defence said Britain might have to ask for an extension to the 10 year clearance period. "Clearly we are committed to the Ottawa Treaty but the Falklands do present particular difficulties because of the nature of the terrain. We are currently considering how to deal with this in the light of our treaty obligations," he said.
Yesterday the Defence Evaluation and Research Agency's technical manager with responsibility for the Royal Engineers' equipment said that although the latest technology might be adaptable to the job, he had not been asked to look into it yet. John Hambley said that during the 1980s, experts had looked at either burning or digging up the mines by remote control as well as at detecting them with ground-penetrating radar systems. However, all the methods had their drawbacks.
"The decision was made that it was better to leave the mines where they were. What we had was not going to be reliable enough, and it was still quite costly," he said.
The Royal Engineers have cleared about 1,400 mines since the war, mostly in sensitive areas. But they did so by lying on their stomachs and using probes, a painstaking and labour-intensive process. For example, they cleared a path to a windmill so that local people could gain access to carry out maintenance work.
Wendy Teggart, general manager of the Falkland Islands Government's London office, said the islanders had felt that even if the mines were cleared they might not be confident enough to use the land.
"As a Falkland Island mother myself I would not be happy with my children playing on an area that was cleared," she said. "With the best will in the world, someone could say they believed it was clear when it was not."