The French army general charged with the rebuilding of Paris' fire-ravaged Notre Dame is rebuked by the Government after telling the chief architect to "shut his mouth" in a sign of tension over the cathedral's future appearance.

Key points: French President Emmanuel Macron has said he is in favour of adding a "contemporary" touch to the spire.

French President Emmanuel Macron has said he is in favour of adding a "contemporary" touch to the spire. The lead architect is of the view the spire should be exactly the same but was told to "shut his mouth" by a French general in charge of the rebuild

The lead architect is of the view the spire should be exactly the same but was told to "shut his mouth" by a French general in charge of the rebuild The General says the design will be decided in 2021 and people should stop the "hustle and bustle" over the issue in the meantime

General Jean-Louis Georgelin lost his cool with architect Philippe Villeneuve in a dispute over whether to replace the spire — which was toppled in the April 15 blaze — with an exact replica or mix things up with a modern twist.

"As for the chief architect, I have already explained that he should shut his mouth," General Georgelin said to gasps of astonishment at a meeting of the cultural affairs committee of the lower house National Assembly on Wednesday.

Culture Minister Franck Riester tweeted on Thursday that General Georgelin's outburst was "not acceptable".

"Respect is a cardinal value in our society. As public officials, we must be exemplary," Mr Riester said.

French Army General Jean-Louis Georgelin (pictured) has taken aim at the Notre Dame architect. ( AFP )

President Emmanuel Macron — who appointed General Georgelin to head the massive reconstruction project — has said he is in favour of adding a "contemporary" touch to the spire.

But Mr Villeneuve insists it must be redone exactly as it was before.

General Georgelin, a former army chief of staff, suggested that "we move ahead in wisdom so that we can serenely make the best choice for Notre Dame, for Paris, for the world".

He said the final appearance of the cathedral would be decided in 2021, and called in the meantime for the "hustle and bustle" over the issue to stop.

The general confirmed the five-year timeframe set by Mr Macron for rebuilding the cathedral — a deadline some experts see as too ambitious.

Mr Villeneuve, however, has said the target could only be met if the spire was rebuilt to resemble its former self.

'Remains in danger'

The spire and roof of the Notre Dame Cathedral in Paris burned down in April. ( Reuters: Benoit Tessier )

Notre Dame, part of a UNESCO world heritage site on the banks of the River Seine in Paris, lost its gothic spire, roof and many precious artefacts in the blaze.

Paris prosecutors said in June a poorly stubbed-out cigarette or an electrical fault could have started the fire and opened an investigation into criminal negligence.

Last month, the culture ministry said nearly 1 billion euros ($AU1.6 billion) had been pledged or raised for the gargantuan reconstruction.

The cathedral is still enveloped in scaffolding and plastic sheeting.

General Georgelin told MPs that Notre Dame "remains in danger".

"The phase of securing the edifice is not over. It will be done when the scaffolding around the spire has been dismantled," General Georgelin said, and warned of winter gales threatening to "destabilise" the temporary, protective structure.

On the positive side, Notre Dame "no longer seems to be emitting lead" — a major concern shortly after the disaster that saw hundreds of tonnes of lead in the roof and steeple melt.

Mr Villeneuve, the cathedral's architect since 2013, last month said: "Either I restore it identically, it will be me, or they make a contemporary spire and it will be someone else."

AFP