With paintings by impressionist masters fetching record prices on a booming international art market, Egypt is sitting on a little-known gold mine.

At up to $10 billion, the estimated value of the contents of just two Cairo art museums approaches a quarter of the country's foreign debt.The Mohammed Mahmoud Khalil museum, a small Moorish-style palace in the island residential area of Zamalek, houses impressionist and post-impressionist works worth anything from $500 million to $5 billion.

"I think we have one of the most important collections in the world," said museum director Ahmed Sami.

"Its contents have no equal in any other museum," said Abdul Wahab Morsi, head of the government Museums Department, who says the collection could be worth $3 billion to $5 billion.

The most valuable piece is an 1889 painting by Paul Gauguin, "Life and Death," worth an estimated $60 million.

Then there is a Van Gogh valued at $30 million, a painting in colored inks on wood by Toulouse-Lautrec and more than 400 other canvases - not to mention several Rodin bronzes - which could fetch huge sums at auction.

Yet only 30 to 40 people, mostly foreigners and art students, visit the museum on an average day. There is no catalogue, not even a typed list of contents. They ran out two years ago.

An equally valuable collection of paintings, sculptures and other works gathers dust under lock and key at the former Gezira museum near Cairo's new opera house in Zamalek.

The Gezira museum opened more than 30 years ago to house art treasures confiscated from Egypt's wealthy elite after the 1952 revolution that overthrew the monarchy.

Little known and rarely visited, it closed its doors four months ago for a two-year inventory that Morsi says will enable authorities to find out just what Egypt owns.

A Rubens, a Renoir, a Delacroix, a Manet and sketches by Picasso are among more than 700 paintings in the Gezira storerooms.