Since mid-January, an additional 8,500 people have died in France compared to the usual figures over the last eight years.
The French Institute of Health Watch (InVS) noted that the flu epidemic was likely behind the sharp increase, reported French channel BFM TV.
However, epidemiologist Daniel Lévy-Bruhl told the AFP news agency that exact details were impossible to deduce, as "the word flu is rarely written" on death certificates.
Many of those who died were over the age of 65, he added, and while they often were suffering from the flu, it would have been other resulting complications that led to their deaths.
Flu swept across France this winter, an epidemic made worse by the fact that the strain of the virus was slightly different to the one used in the vaccination - meaning that many people who were jabbed still fell ill.
Experts said the worst was expected in mid-February, and late last month hospitals reported a crisis situation after running out of beds.
While doctors note that the epidemic is finally beginning to decline, there were still 316,000 new cases reported nationwide last week, taking the total number of cases brought to doctors to almost 2.7 million since the epidemic began.