A report commissioned by the French president, due to be published later on Friday, is expected to recommend a change in the French law to allow the return of thousands of African works of art.

President Emmanuel Macron started this ball rolling a year ago when - on a visit to Burkina Faso - he said that within five years France should have started the process of temporary or definitive restitution of artworks to Africa.

The report he then commissioned recommends a dramatic shift in the debate.

Basically its authors - Bénédicte Savoy of France and Felwine Sarr of Senegal - say that any work of African art from the colonial era that is now in French museums should be presumed to have been acquired without fully informed consent, unless it can be proved otherwise, and they want the law changed so the pieces can be returned.

In theory this could open the door to a wholesale restitution of artworks, and the emptying of museums like the Quai Branly in Paris where there are some 70,000 pieces from Africa.

Supporters hope that other European museums - like the British Museum in London - might also come under pressure.

In practice there is some scepticism about the viability of the proposals.

The idea is that African governments would first have to submit demands for specific artworks, and it is not clear how many are ready to do so.