It was surpassed only by unrest in Egypt and the crash of the Asiana Flight 214 passenger jet in San Francisco, according to a spokeswoman for Influence Communication.
Media from as far away as China, New Zealand and Saudi Arabia devoted considerable space to the tragic railway derailment.
On social media, there was an outpouring of anger against the Montreal, Maine & Atlantic Railway, whose train was hauling 72 tanker cars when it barrelled out of control into the quiet Quebec community early Saturday before exploding.
Eve Couture, director of consulting services at Influence Communications, says the firm analyzed the media content of 160 countries.
"On television, in the newspaper, and the radio, the situation in Lac-Megantic is the third most important news story in the world," she said.
Couture said Quebec events rarely get so much attention in world media.
The train, which had no crew aboard but was carrying vast quantities of fuel when it careened into the small town, grabbed sensational headlines such as ''Canada's Train of Death" or "The Explosion of A Ghost Train."
The story also raged across social media, with the terms "Lac-Megantic" or "Megantic" showing up 38,000 times on Twitter in the two days since the tragedy, said Influence Communication.
After first expressing interest in the initial details of the tragedy, social media users then turned their attention to possible causes.
A number of posters on Facebook and Twitter slammed the top executives of the Montreal, Maine & Atlantic Railway.
"The subject that is taking over is Montreal, Maine & Atlantic Railway," said Couture. "The attention isn't on the deaths or the news but more on the causes and the reaction of the company."
The Maine-based railway firm sent out a news release on Sunday with its reaction to the tragedy. The French version appeared to have been done by a computer translation program.Suggest a correction