By Andrew Gray, John Irish and Sabine Siebold

VILNIUS NATO leaders gather for a summit in Vilnius on Tuesday seeking to overcome divisions on Ukraine's membership bid after a deal to lift Turkey's block on Sweden joining the military alliance.

The summit in the Lithuanian capital will be dominated by the repercussions of Russia's invasion of Ukraine, with leaders set to approve NATO's first comprehensive plans since the end of the Cold War to defend against any attack from Moscow.

Diplomats said differences were narrowing over Ukraine's push for NATO membership. While NATO members agree Kyiv cannot join during the war, they have disagreed over how quickly it could happen afterwards and under what conditions.

Ukrainian President Volodymyr Zelenskiy, who has been invited to attend the Vilnius gathering, has been pressing NATO to give his country a clear pathway to membership in the summit communique so that it can join soon after the war is over.

"We are still working on the wording ... but we already understand the fact that Ukraine will be in the Alliance," Zelenskiy said on Twitter on Monday evening.

He said Ukraine was "working to make the algorithm for gaining membership as clear and fast as possible".

NATO members in Eastern Europe have backed Kyiv's stance, arguing that bringing Ukraine under NATO's collective security umbrella is the best way to deter Russia from attacking again.

NATO was formed in 1949 with the primary aim of countering the risk of a Soviet attack on allied territory.

Countries such as the United States and Germany have been more cautious, wary of any move that they fear could draw NATO into a direct conflict with Russia, and potentially spark a global war.

Assertions that "Ukraine's rightful place is in NATO" and that it will join "when conditions allow" are among the phrases being discussed for the final text, diplomats say.

Some of Ukraine's eastern allies want the word "invitation" or "invite" to be included.

Negotiations have also focused on what conditions Ukraine would have to meet to join NATO and how its progress should be tracked, diplomats say.

JOURNEY WITHOUT A MAP

NATO Secretary General Stoltenberg said on Monday he had proposed Ukraine could skip a Membership Action Plan (MAP) - a process for meeting political, economic and military goals.

"I am absolutely certain that we will have unity and a strong message on Ukraine," Stoltenberg told reporters.

Moscow criticised the two-day summit in advance. According to the RIA news agency, Russian Foreign Ministry spokesperson Maria Zakharova predicted it would be "a colourful spectacle in the worst traditions of Western manipulation".

Russia's invasion of Ukraine in February last year prompted Nordic neighbours Finland and Sweden to abandon decades of military non-alignment and apply to join NATO.

Finland became NATO's 31st member in April but Sweden's accession has been held up by a dispute with Turkey.

That impasse appeared to have come to an end after talks in Vilnius on Monday evening, when Turkish President Tayyip Erdogan agreed to send Sweden's application to the Turkish parliament for ratification. Stoltenberg hailed the move as "historic".

Turkey had accused Sweden of not doing enough to crack down on militants that Ankara sees as terrorists, mainly members of the Kurdistan Workers Party (PKK), considered a terrorist organisation by Turkey, the EU and the United States.

Sweden, backed by Stoltenberg and many NATO members, said it had kept all its undertakings to Turkey on the issue.

But Swedish Prime Minister Ulf Kristersson and Erdogan agreed to further steps on Monday evening, including establishing a new "Security Compact" on fighting terrorism.

The two also agreed to step up economic cooperation and Sweden committed to support efforts to revive the moribund process of moving Turkey closer to the European Union.

"This has been a good day for Sweden," Kristersson told reporters, saying the joint statement represented "a very big step" toward final ratification of Sweden's NATO membership.

(Additional reporting by Ronald Popeski and Lidia Kelly; Editing by Stephen Coates)