A rising tide of travellers seeking out the new frontier of Egyptian tourism is threatening priceless rock art preserved for millennia in one of the most-isolated reaches of the Sahara.
In Egypt's southwest corner, straddling the borders of Sudan and Libya, the elegant paintings of prehistoric man and beast in the mountains of Gilf Kabir and Jebel Ouenat are as stunning in their simplicity as anything by Picasso.
But lying 500 kilometres (330 miles) from the nearest habitation, the desert offers little sanctuary for these masterpieces and any effective protected designation first requires a deal between the three sometimes quarrelsome nations.
Not only the rock art is at stake, but the region's entire cultural and natural heritage.
"You can't estimate the amount of damage done," says Dr Rudolph Kuper, a German archaeologist involved in trying to protect the art, mostly dating from when the desert was a receding prairie 5,000-7,000 years ago.
"People put water or oil on the paintings to make the faded colours look brighter, causing irreparable damage," he says.
The story is even more tragic just across the border in Libya, where the delicate brush strokes of human figures at Ain Dua appear to have been shot at by bored soldiers.
Nearby, a painted cave is filled with rubbish while outside a giant portrait of Bob Marley shimmers garishly in the white of the desert.
Paying up to 10,000 dollars for a two-week expedition, travellers drive through the desert to reach Gilf Kabir, site of the Cave of the Swimmers made famous by the 1996 film "The English Patient."
While only a handful came here in the 1980s, the numbers have been rising steadily through the 1990s as some of the millions of tourists visiting Egypt seek out something more exotic than the sandy beach of a Red Sea resort.
"By 2006 there were probably 800 people coming and this year we expect more than 1,000," says Kuper.
Rock art specialist Tilman Lenssen-Erz says that in prehistoric times the sites would have been known for thousands of square kilometres (miles).
"This was a place so highly charged with symbolism and with the world views that were fixed there in the rock art that it would have been like a huge cathedral in a European context," says Lenssen-Erz.
"People from far away would know about the significance of the religious power that is collected in this place ... where the supernatural powers of the world were fixed on rocks making the whole area a sacred landscape."
Even more recent artefacts like the world's westernmost example of ancient hieroglyphics known as Meri's rock, to the northeast of Gilf Kabir, have not gone unscathed by the passage of modern man.
The hieroglyphs are evidence that, contrary to the idea that pharaonic trade with sub-Saharan Africa only went via the Nile Valley, the ancients had a major trading route cutting straight through the desert.
Last year, someone embellished the ancient writings with a giant engraving of a topless woman.
"You can't put barbed wire around it so we developed the idea of mental fences," Kuper says of the importance of educating guides and tourists alike.
Saad Ali, a young tour operator based in the oasis of Farafra who also runs the Farafra Development Institution NGO, also realised that the only long-term solution was through education.
"We always arranged trips to clean up the desert and every year we found more rubbish so we found the solution is to train the guides," he says.
"Now it's changed a lot. Last year we went to clean up and we collected only 4.5 tonnes of rubbish while the year before it was 11 tonnes."
His next target is tour operators working out of Cairo, still largely unaware of the damage they wreak.
Kuper says that such programmes help to manage "70-80 percent of people" but that others -- tourists still living with a colonial mentality and Cairo-based expats who take away artefacts in their 4x4s -- are difficult to control.
With untold damage already wrought, getting Egypt, Libya and Sudan to agree on policing the militarily sensitive area is a conservation conundrum.
The hope is to have the area designated as a trans-boundary cultural landscape UNESCO World Heritage site, but that requires the three nations to all first declare individual national parks.
So far, only Egypt has designated a park, but officials from all three countries are due to meet in Cairo in December in the hope of hammering out a deal, despite their occasionally fraught diplomatic relations.
With the support of the Supreme Council of Antiquities, Kuper and Prof Mustafa Fouda from the Egyptian Environmental Affairs Agency want to build a museum-cum-educational centre in the oasis of Dakhla, the jumping off point for most trips to Gilf Kabir.
"Hopefully we can make our dreams come true, with a museum to explain the relationship between man and the desert, to explain how man can make use of the resources in a sustainable way," says Fouda.
Pending the politicians' decision, Kuper says that recently some tourists have returned to the Cave of the Swimmers to try to erase their names. For the desert's desecraters, it seems the writing is on the wall.