PHOTOS: Inside Notre Dame Cathedral

Rubble and the cross inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)

A month after a fire engulfed Notre Dame Cathedral, workers are still trying to ensure the edifice is safe enough for the restoration process to begin, French Culture Minister Franck Riester said.

Riester and Canadian Prime Minister Justin Trudeau wore hard hats for a visit Wednesday inside the Gothic church.

Trudeau said he wanted to show Canadians' solidarity "toward our French cousins." After the devastating April 15 fire, he said one "can't help but marvel at how so much was saved."

Operations to secure and conserve the cathedral must be completed before restoration works can start, Riester said, adding that robots were removing gravel from within to be examined both by ministry experts and police seeking clues about the fire's origin.

Most paintings, relics and the Crown of Thorns purported to have been worn by Jesus at his crucifixion are being conserved at the Louvre Museum. Several works still cannot be accessed, though they are safe, the culture minister said.

A collection of funds for the restoration has so far brought in about 850 million euros (952.2 million dollars), he said.

"It's way too early to know if we have enough money or even too much money to restore Notre Dame of Paris," Riester said. He noted there can be a difference between pledges and what is actually provided, and added that with no "diagnostic" of the damage, a price of the restoration work isn't yet known.

"The needs are obviously colossal," he said. (AP)

PHOTOS: Fire breaks out at Notre Dame Cathedral in Paris »

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Workers stand near damages and rubble during preliminary work inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)
A worker stands on scaffolding during preliminary work inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)
Damages and rubble are pictured during preliminary work inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)
Damaged chairs are pictured inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)
A worker stands on scaffolding during preliminary work inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)
Bells are pictured inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)
A worker stands on scaffolding during preliminary work inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)
A worker stands on scaffolding during preliminary work inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)
A picture shows a protective net inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)
Damages and rubble are pictured inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)
Bells are pictured inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)
Rubble and the cross inside the Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)
Rubble and the cross are pictured under a protective net inside Notre Dame de Paris Cathedral, May 15, 2019 in Paris. (Photo: Philippe Lopez/Pool via AP)

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