"I believe Germany is fulfilling its part and we don't need to talk about new issues related to this question at the moment," Merkel told the ZDF broadcaster when asked about the Der Spiegel magazine report of the U.S. request.

Der Spiegel reported on Saturday that U.S. Defense Secretary Ashton Carter had sent a letter asking for a bigger military contribution from Germany, a week after parliament approved a plan to join the campaign in Syria.

A German Defense Ministry spokesman confirmed a letter had been received from the United States and its content was under consideration, giving no further details.

Der Spiegel said the letter did not make specific demands and was similar to requests sent to other U.S. partners.