Lithuanian President Gitanas Nauseda will meet Ukrainian President Volodymyr Zelenskiy in Kyiv on Wednesday to discuss NATO as Ukraine seeks to enter the alliance.

Zelenskiy on Tuesday stepped up calls for Ukraine to receive a "political invitation" to join NATO at a July 11-12 summit of alliance members in Lithuania.

NATO members are close to agreeing incremental steps to strengthen ties with Ukraine by the Vilnius summit but have yet to resolve differences over how to address Ukraine's desire for membership.

Lithuania has been one of the staunchest supporters of Ukraine in NATO and the EU, and has been calling for accepting it into both. Lithuania is buying NASAMS air defence systems for Ukraine from a Norwegian company.

The presidents will discuss "the NATO summit agenda", Ukraine's European Union membership negotiations, and European support for Ukraine, Nauseda's office said in a statement.

Nauseda will then head to a European Union leaders' summit in Brussels on Thursday and Friday. (Reporting by Andrius Sytas in Vilnius; editing by Robert Birsel)