Worshippers in hard hats have gathered among fire debris for Notre Dame’s first mass since going up in flames two months ago.

A small congregation of about 30, led by Paris’ Archbishop Michel Aupetitin, donned the protective wear to show that life goes on at the historic Gothic Cathedral.

Occasionally during the ritual attendees lifted their head wear to read from the bible or receive communion while standing near piles of burnt debris.

Archbishop Aupetitin told reporters afterward that the mass was a “moment of emotion”.

“Many of the people who attended work in the cathedral. They were touched. It’s their house,” he said.

“For believers, it’s a moment of hope. The cathedral will be back.”

He acknowledged it was “a bit strange” to celebrate mass with a helmet.

The Archbishop of Paris Michel Aupetit, holds the first mass in a side chapel of Notre Dame Cathedral. Photo: Getty

Notre Dame’s spire and part of the roof structure collapsed when the medieval church caught a ablaze on April 15, burning for nine hours.

The catastrophe sparked shock and grief and led to billionaires, business leaders and others pledging 850 million euros ($1.4 billion) for its reconstruction.

The French government said so far less than 10 per cent of the money had been received.

Thirty white hard hats for worshippers at Notre Dame’s first mass. Photo: Getty

The first mass, which commemorates the cathedral’s consecration as a place of worship, was held in a side-chapel left undamaged by the fire.

The service was broadcast live on a religious TV channel that showed poignant images of the blue sky through the collapsed roof, and black rubble still clogging the building.

French President Emmanuel Macron has set a five-year deadline to complete reconstruction of the church and an international competition will help decide a new design for the spire.

Between 60 and 150 workers each day are continuing efforts to stabilise the building which is still in danger of partial collapse.

Fire spread through the historic Notre Dame in Paris’ city centre on April 15. Photo: Getty

Archbishop Aupetit said the mass was a “beautiful symbol”.

“It is a message of hope and thanks to all those who were moved by what happened to this cathedral,” he said.

-with AAP