Speaking after talks with NATO Secretary General Jens Stoltenberg, Zelensky said the G7 promises should be seen "not instead of NATO, but as security guarantees on our way to integration".

"We can state that the results of this summit are good, but should we receive an invitation, then that would be the optimum," he said at NATO's summit in Vilnius.

Later in the day, the G7 group of major industrial powers is expected to announce a plan for long-term guarantees to help Ukraine defeat the Russian invasion and deter future aggression.

But the Ukrainian leader had also hoped that the NATO summit in Vilnius would have issued an invitation with a clear timetable for Kyiv to formally join the NATO alliance.

"The best guarantee for Ukraine is to be in NATO," Zelensky told reporters.

Zelensky said he was "confident that, after the war, Ukraine will be in NATO".

"We'll be doing everything possible to make it happen," Zelensky said.

NATO leaders agreed Tuesday Ukraine would get an invite when "conditions are met".

"I understand this as 'when it will be safe on our land'," Zelensky said.

Stoltenberg was sympathetic to Zelensky's position and stressed the importance of the progress he said Ukraine had made at the summit.

He noted that Zelensky was about to join the 31 NATO leaders at an inaugural meeting of the Ukraine-NATO Council, and that several members were boosting bilateral assistance.

"Today, we meet as equals, I look forward to the day we meet as allies," Stoltenberg said.

"We must ensure that when this war ends, there are credible arrangements in place for Ukraine's security, so that history does not repeat itself," he said.

"I therefore welcome that many allies will today commit to providing long term security assistance to Ukraine," he continued.

"This will help deter any future aggression from Russia after this war ends and it complements the support provided by NATO."