Germany plans to quickly purchase a stake in EADS to preserve its influence over the aerospace group, fearing that Daimler could unload shares it holds in the company on the open market, a document obtained by Reuters showed.

Under current plans by the German economy ministry, state-owned development bank KfW will increase its EADS stake to 13 percent from 1 percent in two steps to be carried out by the end of this year.

That would include KfW buying a 7.5 percent EADS stake from Daimler.

"The entire transaction needs to be carried out fast, otherwise there is a concrete danger that Daimler could sell its shares on the open market. With that, the Franco-German balance would be lost to Germany's detriment," the document from the ministry said.

KfW declined to comment.

A Daimler spokesman reiterated that the carmaker intends to further reduce its EADS stake by the end of this year and that talks with the German government were very constructive.

(Additional reporting by Christiaan Hetzner and Arno Schuetze)