The scaffolding around the spire of Paris's Notre-Dame cathedral has begun to come down, the authority charged with restoring the monument after a devastating 2019 fire said on Tuesday.

The spire should be entirely visible by the time the Olympic Summer Games open in the French capital on July 26, it said.

"The dismantling of the scaffolding has started and will continue over the coming months," the restoration authority, Etablissement Public, told AFP.

The scaffolding reached 100 metres (330 feet) in height, weighed 600 tonnes and contained 70,000 metal parts.

The spire has been covered in lead, a material that has caused much debate because of its potential toxicity.

In December, the cathedral regained its great cross, and got a new golden rooster to replace the old one that was destroyed in the April 15, 2019 fire.

Initially, President Emmanuel Macron promised the UNESCO-listed building would be fully restored by the time the Games open, but the date has since been pushed back to December this year after restoration work hit several snags.

Authorities have still not determined the cause of the fire, although they believe it was started accidentally.

Annual visitor numbers are expected to rise to 14 million after the cathedral's reopening, from 12 million before the disaster.