France must be given the option of buying shares from media group Lagardere as part of a proposed merger between EADS and BAE, a French government source said on Monday.

"If France does not even have the possibility to consider buying the stake which Lagardere wants to sell, then for us it is not doable," the source said.

He added that he did not think an agreement could be reached on the planned mega-merger of the European aerospace group and British defense company by an October 10, adding that Paris had no problem in having an equal stake with Berlin as part of the deal.

Britain has called for a cap to be placed on existing state shareholdings to avoid too much government influence in the proposed venture.

(Reporting By Emmanuel Jarry; writing by John Irish; Editing by Christian Plumb)