Berlin, Ukraine's second biggest supplier of arms to resist the Russian invasion, had already announced a new weapons package worth 2.7 billion euros for Kyiv in May, ahead of a visit by President Volodymyr Zelensky.

A senior government official on Monday had said that Germany would make a "very substantial" new pledge of military equipment for Ukraine at the NATO meeting.

Since Russia invaded Ukraine in February last year, Germany has dropped a traditionally pacifist stance and sent a vast array of weaponry to Kyiv, from air defence to artillery systems. It is now Ukraine's second largest arms supplier after the United States.

Berlin earlier this year started sending advanced Leopard battle tanks to Ukraine, after months of pleas from Kyiv for the heavy weapons to bolster its fightback against Russia.

Ukrainian and German politicians have been calling for rapid resupply of tanks given the destruction of the armaments by Russian forces.

The two-day summit is set to be dominated by the alliance's response to Russia's war on Ukraine and Kyiv's push for NATO membership.