THE first official government website in the world to document UFO sightings has collapsed under a stampede by the public to gain access.

The National Centre for Space Studies, the French equivalent of Nasa, opened the website on Thursday, unveiling an archive of documents about hundreds of unidentified flying object sightings in France over the past 50 years.

Such was the excitement and scramble to pick through this treasure trove that the website was overloaded and “crashed”.

The archive includes photographs, police records of interviews with witnesses and even video recordings.

It covers cases ranging from the obviously ludicrous — there are numerous sightings of little green men — to several that have stumped even the most sceptical scientists.

“It is a world first,” said Jacques Patenet, an aeronautics engineer in charge of the space centre’s “study of nonidentified aerospatial phenomena”.

Known as OVNIs in France, UFOs have always generated intense public debate in Paris as well as conspiracy theories about American cover-ups and findings considered too sensitive or too alarming for public consumption.

“Cases such as the lady who reported seeing an object that looked like a flying roll of toilet paper” were clearly not worth reporting, said Patenet. But other incidents involving multiple witnesses have for long been baffling the experts.

Of the 1,600 cases registered since 1954, almost a quarter are classified as “D”, meaning that “despite good or very good data and credible witnesses, we are confronted with something we cannot explain”, said Patenet.

For example, in 1994 the crew of an Air France flight from Nice to London saw a giant disk that seemed to keep changing shape and colour. After a minute or so it disappeared.

On January 8, 1981, in southern France, a man working in a field reported hearing a strange whistling sound. He saw a saucer-like object about 8ft in diameter land in his field about 50 yards away.

The object took off almost immediately, leaving burn marks. Investigators took photographs and collected and analysed samples, but they have not been able to explain the phenomenon.

Nearly 1,000 witnesses said they saw flashing lights in the sky on November 5, 1990, but this was just rocket fragments falling back into the Earth’s atmosphere.

Perhaps the best documented European incident involved the scrambling of two Belgian air force jets in March, 1990, to investigate an aircraft flying over the south of the country in a manner “outside the normal performance envelope of any air-plane”, as the chief of Belgian air force operations described it afterwards.

The new French website, once reactivated, will be updated whenever there is a new sighting, but experts in the field were doubtful that the archive would shed any light on the mystery.

“It’s useless,” said Jean-Pierre Petit, a retired aerospace researcher, referring to the archive. “It’s just reports from the gendarmes.”

He said that the police had long ago been issued with equipment for gathering chemical samples and that this had often been used. “What is the result of that research? That is what we want to know.”

It is not the first time that the French government has released information about UFOs. In 1999, the Institute of Higher Studies for National Defence published a 90-page report called UFOs and Defence: What Must We Be Prepared For? It has become a bible for UFO enthusiasts the world over.

It says in the preamble: “The accumulation of well-document-ed observations compels us now to consider all hypotheses as to the origin of UFOs, especially extraterrestrial hypotheses.”

The report discusses 15 cases, including one in which British jet fighters were scrambled from RAF Lakenheath to investigate mysterious objects over East Anglia in 1956.

It says that hoaxes are easily detectable and calls the position of America “still one of denial”. It concludes: “The physical reality of UFOs, under control of intelligent beings, is almost certain.”

The American attitude is exemplified by the former Arizona governor Fife Symington, who trotted out an aide dressed as an alien 10 years ago to spoof the frenzy surrounding mysterious lights in the Phoenix sky.

Now he says he saw the lights and believed from the start that they were extraterrestrial. Symington, who faced fraud charges at the time, said this week he did not need the problems such an admission would have created.

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