"We're not going to discuss an invitation at the Vilnius Summit, but how we can move Ukraine closer to NATO," Stoltenberg said.

"I'm confident that we will find a good solution and consensus."

In a symbolic step alliance leaders are aiming to hold a first session of a NATO-Ukraine Council with President Volodymyr Zelensky in the Lithuanian capital, Stoltenberg said.

The move represents an upgrade in political ties and will give Kyiv a more equal seat at the table "to consult and decide on security issues", Stoltenberg said.

But it is seen as little compensation for any failure to make headway on Ukraine's push to join the US-led military alliance's protective umbrella.

NATO countries are still wrangling over what to do about Kyiv's calls for a clear sign it will be accepted once Russia's war ends.

NATO nations in eastern Europe have pushed for a better roadmap for Ukraine to obtain membership.

But key allies like the United States and Germany are reluctant to go much beyond a vague pledge in 2014 that Ukraine will join one day.

German Defence Minister Boris Pistorius suggested Friday it was possible some requirements for membership could be eased if Ukraine was eventually ready to join.

Diplomats say that as an interim measure before it joins, allies are debating giving Ukraine security assurances of guaranteed weapon supplies to help it defend itself.

The United States, United Kingdom, France and Germany are currently taking the lead on those discussions, diplomats said.

NATO countries have already supplied weaponry worth tens of billions of dollars to Ukraine since Moscow launched its all-out invasion last February.

Stoltenberg is also pushing for NATO members to commit to a multi-year package of help to bring Ukraine closer to alliance standards.

The aim has been to provide 500 million euros a year for the programme, but diplomats say so far the allies have not reached that figure.