The chief of the British Army said today the detention of a British military group in Mexico was due to a "grave misunderstanding" and said the men had been there only to explore underground caves.
The six cavers, four of them members of the British military, were rescued from a cavern late on Thursday after spending 11 days trapped underground by floodwaters.
But a diplomatic row broke out between London and Mexico on Friday when Mexican President Vicente Fox refused to accept Britain's explanation of what they were doing in the caves.
Mexico's attorney general's office said it was investigating media reports that the cavers were scouting for deposits of potentially radioactive materials. The men have been detained and questioned by immigration officers.
General Sir Michael Jackson, chief of the general staff of the British army , said the men were on an expedition designed to improve their skills and were simply exploring the caves.
"It seems to me there is quite a grave misunderstanding," he told BBC television. "This was a joint service adventure training expedition. We do a lot of that to bolster initiative and courage.
"It seems to me that their purpose was to explore these caves further than they had already been explored."
The Mexican government is upset it was not told in advance of the presence of the expedition, most of whose members belonged to an enthusiasts' group made up of active and retired British soldiers and civilians in the Ministry of Defence.
Mexico does not allow foreign military exercises on its soil.