The expansion could double the 120 million doses currently manufactured at the plant within five years, a spokesperson at the company told In-PharmaTechnologist.com.
The added capacity at the plant in northern France will allow increased production of the firm's yellow fever and polio vaccines, as well upping manufacture of the vaccine to protect against the avian flu virus, H5N1.
Work at the site has already begun, and is due to be complete by 2009.
The investment in the Val de Reuil plant is the largest capital investment in France to date for the company, and will result in formulation, filling and packaging capacity facilities, which are intended to help significantly reduce time to market for the firm's vaccines.
This latest cash boost follows on from the $160m (€118m) sum put towards a new influenza vaccine manufacturing facility in the US in 2005, due to come online for the 2008/9 flu season and double production capacity.
While the majority of the manufacture of the bird flu vaccine approved yesterday by the FDA will take place at the firm's Swiftwater plant in Pennsylvania, the increased capacity at one of the company's European plants suggests that Sanofi holds out hope for further demands for its vaccine on the other side of the Atlantic.
According to the FDA, Sanofi Pasteur will not be selling the approved vaccine commercially in the US.
Instead, it has been purchased by the US federal government for inclusion within the US strategic national stockpile to be distributed as and when it is needed.
In November last year the company announced an agreement with the US Department of Health and Human Services for the production of bulk concentrate of a new type of H5N1 pre-pandemic vaccine.
The agreement was valued at up to $117.9m, dependent on the number of doses that can be formulated form the bulk material.
The company also has several agreements within Europe, including a contract with the French Ministry of Health to produce a 1.4 million dose stockpile of H5N1 vaccine with a clause to be called upon to provide enough vaccine to protect 28 million people in France should a pandemic strike.
The firm also has an agreement with the Italian Ministry of Health.
Sanofi Pasteur is the only vaccine manufacturer, indeed the only pharma firm, involved in the Flupan project funded by the European Commission.
The project aims to improve pandemic preparedness in the EU by producing and testing experimental vaccines, compiling libraries of reagents and investigating new cell culture vaccine production techniques.
Sanofi itself is responsible for producing a vaccine to combat another flu strain with pandemic potential, H7N1, that will be used in a Flupan clinical study.