French officials have warned that fraudsters are taking advantage of the Notre-Dame fire to fool donors into handing over cash believing they are helping to rebuild the gutted Paris cathedral.

The French Heritage Foundation, which has so far collected more than €13 million from individual donors to help restore the Gothic landmark, said any phone or email appeals were fake.

"A number of scams have been flagged to us both in France and abroad," the foundation said, insisting it issues no appeals by phone, mail or email for donations. "All of these initiatives are fraudulent."

The foundation is accepting international donations through its website, its Facebook page or by PayPal - or at a Paris metro station and by SMS for those in France.

Corporate donations have now topped €500 million.

French Culture Minister Franck Riester has also warned people to be wary of websites claiming to support the reconstruction of Notre-Dame, which suffered heavy damage in Monday's blaze.

French President Emmanuel Macron has vowed to rebuild the monument by 2024, when France hosts the summer Olympics.

Meanwhile, a conservation architect says a five-year deadline to rebuild Notre Dame is an "optimistic one".

Speaking to RTÉ's Morning Ireland, John Beauchamp said that five years was not a long time, especially to rebuild a cathedral like Notre Dame.

He said the extent of the damage is still unknown, adding that it will take a long time for the cathedral to dry out.

Mr Beauchamp said no one knew yet if the remaining structure would be capable of carrying the load of a new roof.

In addition, he said, a temporary roof must be put in place as soon as possible in order to protect the interior of Notre Dame.

Mr Beauchamp is overseeing the restoration of St Patrick's Cathedral in Dublin, which is due to begin this summer, said he believed that human error was to blame for the blaze.

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