It was a mystery from the start: a helicopter sets a world record by touching down on the summit of the world\'s highest mountain but its manufacturer doesn\'t brag about it till nearly a month later. No press conferences, no victory lap in Kathmandu, no major international media blitz.

It is now clear that Eurocopter test pilot Didier Delsalle did land his specially-fitted Ecureuil Astar 350 B3 helicopter on top of Chomolungma on 14 May but the first understated announcement came only on 24 May on the company website without the summit pictures.

Now, a month later, the plot thickens. The Civil Aviation Authority of Nepal (CAAN) which gave a month-long permission to Eurocopter to conduct 'test flights\' in the Everest region says Delsalle has submitted a written statement saying he landed on the on the South Col, 1,000m below the summit.

The pilot wrote to us saying he did not land on the summit while they went around claiming they had made the highest landing, how can they give two different statements? asks Keshab Raj Khanal, of CAAN\'s Air Transportation Directorate.

Indeed, why is Delsalle making contradictory statements? Khanal said regulations didn\'t allow him to show us the statement. There are other questions: did Delsalle have permission to even land on the South Col? Given Nepal\'s current political setup could the flights have taken place without a green light from the Royal Nepali Army, which operates its own fleet of Ecureuils? Eurocopter is a subsidiary of the EADS group which also owns Airbus and its website has now posted definitive photographs and videos of the summit landing (w ww.eurocopter.com/everest/). It turns out Delsalle landed first on the South Col on 12 May for practice, then on 14 and 15 May on the summit. The video taken by a fuselage camera shows the skids on top for three minutes and 50 seconds which is nearly two minutes longer than required by F?d?ration A?ronautique Internationale (FAI) the body that needs to recognise the record.

FAI General Secretary Max Bishop told us that the record had not yet been ratified since the final evidence had yet to be studied. In an email, he said: As per FAI rules the claiming authority-in this case France-has up to 120 days from the date of the attempt to put together the claim file. FAI reportedly had staff at Lukla last month which points to a well-planned attempt to break the world record. Why, then, the hush-hush and the denial from CAAN?

The mysterious chopper, its dubious landing and the secrecy surrounding the whole expedition set off wild speculation on mountaineering chatsites about the legitimacy of the claim which were only laid to rest when the photos and videos were posted on the site last week.

The only explanation, one senior government official told us privately, is that Eurocopter did not actually have permission to land on the top of Mt Everest and needed to get all its staff and equipment out of Nepal before announcing it. If that is the case, they have to compensate the Nepal government, he added, maybe we should ask for two Ecureuils.

The authorities are tight-lipped but it is clear that the company couldn\'t have pulled this off without some senior people knowing what was really going on. The fact that the French didn\'t announce it here but waited to get back home gives a shade of doubt, says aviation expert, Hemant Arjyal, but CAAN probably doesn\'t have any rules about helicopters landing on Everest either.

Bhumi Lama of the Nepal Mountaineering Association told us, The permission, whether it was to perform a test flight or to land, was granted by CAAN, they need to clarify what happened.

Eurocopter is making a big promotional splash about the Everest landing at the Paris Air Show this week. To reach this mythical summit definitively seemed to be a dream, Delsalle is quoted as saying in Lukla on 14 May, it was difficult holding (the helicopter) there against the wind.

That doesn\'t sound like someone who landed only on the South Col. Whether they had the permit or not, it is clear a new world record was set last month on Chomolungma.