Secretary General Jens Stoltenberg said he had spoken to Turkey's President Recep Tayyip Erdogan and "agreed to convene a high-level meeting in Brussels before the summit."

"This meeting will include foreign ministers, heads of intelligence, and national security advisors. The aim is to make progress in completing Sweden's accession to NATO," he added.

Stoltenberg spoke to reporters in the Lithuanian capital Vilnius, which will host next month's NATO summit on July 11-12.

Sweden has been a NATO "invitee" since June 2022, but its membership bid, which must be ratified by all 31 member states, has been blocked by Turkey and Hungary.

Western officials have hoped Erdogan would soften his position on the diplomatically charged issue after he secured a hard-fought re-election last month.

Western nations, and the United States in particular, have been pushing Ankara to give its green light, insisting that Sweden has met the terms of a deal agreed with Ankara last year.

That accord includes a commitment to crack down on opposition Kurdish movements, such as the Kurdistan Workers' Party PKK, blacklisted by Ankara which considers them "terrorist" groups.