Germany's foreign minister says major decisions on arms sales are being put on hold as deliberations on forming a new government are underway, amid growing concerns about Turkish action in northern Syria.

The government has come under fire for selling military equipment to NATO ally Turkey, after it became known Turkey was using German-built Leopard tanks in its drive against Kurdish fighters in northern Syria.

Turkey had been pushing for upgrades to those tanks to protect against mines, but Foreign Minister Sigmar Gabriel said Thursday any decisions on "critical projects" will have to wait until his Social Democrats come to a coalition agreement with Chancellor Angela Merkel's Union bloc.

Talks are expected to begin Friday between the two sides, and Gabriel said the issue of arms exports would be discussed.