Daimler, which was in talks to sell a 7.5 percent stake in Airbus parent EADS to Germany’s state bank KfW, is also unhappy with the valuation of the deal.

Changing the ratio would enable the carmaker to exit its investment without booking losses and therefore increase Daimler’s willingness to participate in the deal.

To assuage French and German concerns about safeguarding technology and jobs, EADS and BAE are also considering guaranteed board seats for the governments of France, Germany and Britain, the sources said.

France and Germany also want to make sure that the merged group does not hinder the prospects for rivals such as France’s Dassault and Thales, or Germany’s OHB, they added.

German Chancellor Angela Merkel met French President Francois Hollande to discuss the plans at the weekend, but they failed to come up with any joint decisions.

EADS shares were up 0.8 percent at 25.20 euros at 1112 GMT, while BAE was down 1.8 percent at 328.30 pence.