According to a statement by Türkiye's Communications Directorate, Recep Tayyip Erdogan told Jens Stoltenberg that no progress can be achieved without seeing "concrete steps" by both Finland and Sweden that would meet Türkiye's "rightful expectations."
The steps might include written commitments to a paradigm shift in fighting terrorism and defense industry cooperation, it said.
Meanwhile, Stoltenberg said on Twitter that he held a "constructive conversation" with Erdogan ahead of the NATO summit in Madrid that will be held on June 29-30.
"We discussed the importance of addressing Türkiye’s legitimate security concerns on the fight against terrorism and making progress in the NATO accession process for Finland and Sweden," he added.
Sweden and Finland formally applied to join NATO on May 18, a decision spurred by Russia's war on Ukraine, which began on Feb. 24.
But Türkiye, a longstanding member of the alliance, has voiced objections to their membership bids, criticizing the countries for tolerating and even supporting terror groups such as the PKK and the Fetullah Terrorist Organization (FETO). Their accession requires the unanimous approval of all 30 NATO member countries.
In late May, Türkiye hosted consultations with Swedish and Finnish delegations on their NATO applications in the capital Ankara. Erdogan said the talks had not been "at the desired level."