Six Nations rugby chiefs will hold a crisis meeting on Friday to discuss the future of this year's tournament given the current outbreak of foot-and-mouth in Britain.
The outbreak has already forced the postponement of Saturday's match between Wales and Ireland in Cardiff.
French Rugby Federation (FFR) president Bernard Lapasset said matches planned for March and April now risked being rescheduled.
"The Six Nations Committee will be having an urgent telephone conference on Friday," Lapasset said.
"With the situation such as it is today there is a risk of postponing the matches scheduled for March and April until May," he said.
This weekend's matches between England and Scotland and Italy and France will go ahead as planned.
But doubts now surround matches between France and Wales in Paris on March 17th and Ireland and England in Dublin on March 24th.
Further matches between France and England and Scotland and Ireland on April 7th could also now face rescheduling.
Lapasset said he had contacted both France's agriculture and sport ministries for advice on the issue.
AFP