NATO Secretary General Jens Stoltenberg said Ukraine would get a "positive message on the path to membership" on Tuesday, as leaders of the alliance meet to address the repercussions of Russia's invasion that brought war to their doorstep.

Divisions among the Western military alliance's 31 members on allowing Ukraine in mean there will not be a straightforward invitation for Kyiv to join, something the country's Soviet-era overlord Moscow says would threaten its national security.

But Stoltenberg said Kyiv would get more military aid and an easing of formal conditions to join in a new format of cooperation with the alliance, with the so-called NATO-Ukraine Council due to hold its first session on Wednesday.