PARIS (AFP).- Less than a tenth of the hundreds of millions promised to help rebuild Notre-Dame cathedral in Paris has been donated, the French culture ministry said Friday.

Only 80 million euros of the 850 ($955 million) pledged to reconstruct the iconic monument has been handed over -- and most of that has come in small sums given by ordinary people.

Two of France's richest men, fashion moguls Bernard Arnault and Francois-Henri Pinault, were quick to promise 300 million euros between them after the medieval landmark was devastated by a fire which shocked the world two months ago.

The cathedral's vaulted roof "could still collapse" at any moment, Culture Minister Franck Riester warned Friday as he confirmed the slow pace at which pledges were turning into cash.

The Bettencourt family, who own the cosmetics giant L'Oreal, also said they would put 200 million euros into the pot.

But Riester said the total so far has come from small donations.

Last month, the Archbishop of Paris, Michel Aupetit, raised concerns about the pledges, saying that "the greater part of these donations have not yet materialised".

Cathedral in 'fragile state'
The minister told France radio the huge shortfall as it stands was due to two factors.

"First, you might have people who promised to give but who in the end won't," he said.

"But mostly -- and this is normal -- is that the donations will be handed over as the work advances."

His ministry stressed that the biggest donors want to know when and how their money will be spent.

Riester said his officials were working with the major donors and the four French foundations which launched appeals for Notre-Dame.

He insisted that despite one of the four foundations suspending their appeal last month, "the wave of generosity should continue. Clearly donations are welcome.

"Notre-Dame is still in a fragile state, particularly the vaulted roof which has not yet be secured" and "which could still collapse", Riester added.

His comments come as the first mass will be held in the cathedral on Saturday since it lost most of its roof and spire in the blaze on April 15.

The work to shore up the 12th-century edifice is likely to take several more weeks before the complex studies on the restoration work can be undertaken.

Only 30 people -- half of them clergy -- will be allowed into Notre-Dame for Saturday's service, which will be broadcast live on Catholic TV channel KTO.

Archbishop Aupetit will lead the mass in the Chapel of the Virgin on the east side of the cathedral, which has been confirmed to be safe.

© Agence France-Presse