The derailment happened near the central town of Eseka, Mebe Ngo'o added, in comments made to the state broadcaster Crtv.
"The derailment has caused significant human and material damage but I can't at this time give you any figures," he said.
A ministerial delegation was being sent to the accident site.
A source close to the local Eseka authorities said there were indeed victims, without giving any details.
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"Intervention and security teams have been mobilised," the rail company Camrail said.
The route, between the capital and the economic hub, is one of the busiest in the country, with trains to Chad and the Central African Republic also using the axis which has a poor safety record.
Today's derailment badly disrupted rail traffic.
In 2014, Cameroon began building its first highway between the two towns, but the work is not due to be completed until 2018.
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