Prime Minister Justin Trudeau has offered Canadian steel and lumber to help rebuild France's fire-ravaged Notre Dame Cathedral.

During a visit to Paris on Wednesday, Trudeau called it an "extraordinary honour" to witness the iconic landmark and show Canadians' solidarity with their "French cousins."

"This was a terrible, terrible fire, but we can't help but marvel at how much was saved, even as we did lose so much," he said.

"Canada will stand with France and ensure that we offer all the support, whether it's steel, or wood or whatever help we can. This is truly a piece not just of French history, but of world history that needs to be preserved, and we will be there to be part of it."

The cathedral was devastated by an April 15 blaze. Flames burst through the roof of the centuries-old building and engulfed the spire. That eventually collapsed, followed by the roof.

Prime Minister Justin Trudeau says Canada will offer steel and wood to France to help rebuild the fire-ravaged Notre Dame Cathedral after touring the 850-year-old church Wednesday. 0:20

In a letter to French President Emmanuel Macron, Trudeau said Canadian associations representing steel and lumber producers already have expressed their wish to contribute to the rebuilding effort.

"It is with pride that Canada will help ensure the future of this iconic French symbol for future generations," he wrote.

Christchurch summit

Trudeau is in Paris to sign an international pledge aimed at getting governments and social media companies working together to stem the spread of violent and extremist content online.

The pledge is the centrepiece of today's Christchurch Call to Action summit, co-hosted by Macron and New Zealand Prime Minister Jacinda Ardern — an event planned two months after a terrorist attack on mosques in Christchurch, New Zealand left 51 people dead.

Trudeau also spoke at the VivaTech summit, an annual event celebrating innovation that brings together startups and industry leaders.

Trudeau is holding a series of bilateral meetings with the leaders of Jordan and Norway on Wednesday, and with the leaders of France and New Zealand on Thursday, when the two-day visit wraps up.

Freeland meets U.S. counterpart

His offer of Canadian steel for France's cathedral restoration comes as Foreign Affairs Minister Chrystia Freeland meets with her American counterpart, U.S. Trade Representative Bob Lighthizer, in Washington, D.C., Wednesday in a continued effort to resolve the dispute over steel and aluminum tariffs.

The two are expected to discuss China's ongoing trade actions against both countries, with Freeland making the case that Canada would have a hard time ratifying a revamped NAFTA deal while U.S. tariffs remain in place.

Last June, the U.S. Department of Commerce slapped tariffs of 25 per cent on Canadian steel and 10 per cent on aluminum, citing national security interests.

Canada retaliated with own tariffs of 25 per cent on steel and 10 per cent on aluminum, but also imposed a 10 per cent tariff on several consumer items, targeting U.S. politicians in states where those products are made.

That product list included Kentucky bourbon, lawn mowers, ketchup, maple syrup, appliances, boats, and many other items. The federal government said it was targeting goods that Canadians could otherwise buy from domestic suppliers.

Since then, the Liberal government has rolled back some of the retaliatory tariffs, including ones imposed on recreational boats, while others remain in place.

Freeland will also hold a series of bilateral meetings with members of Congress.