The United States and its allies failed to agree on supplying coveted German battle tanks to Ukraine as Russia issued veiled threats the war could escalate in Europe.

NATO and defence leaders from about 50 countries met at the American Ramstein Air Base in Germany on Friday, the latest in a series of arms-pledging conferences since Russia invaded Ukraine 11 months ago.

European leaders at the meeting again pressed Germany to give the green light for the delivery of German-made Leopard 2 tanks to Ukraine to drive back Moscow’s forces – although no decision was made.

The failure to agree to provide the tanks may signal growing divisions within NATO over supplying such weapons.

Germany’s defence minister Boris Pistorius denied Berlin was unilaterally blocking the delivery of the Leopard 2 tanks to Ukraine, but said his government was ready to move quickly on the issue if there were consensus among allies.