NATO leaders will convene on June 29-30 in Madrid.
Sweden and Finland applied to join the Western defence alliance last month in response to Russia's invasion of Ukraine, but their bids have faced resistance from Turkey, which has accused them of supporting Kurdish militants.
Speaking to the state-run Anadolu news agency during a visit to Madrid, Erdogan's spokesman and chief foreign policy adviser Ibrahim Kalin repeated that progress on the membership bids hinged on how Sweden and Finland respond to Turkish demands. "We don't feel like we are under any time pressure like 'let us get this done by the NATO summit'. What is important here is that Sweden and Finland openly, clearly and concretely put forth what kind of steps they will take regarding counter-terrorism," he added.
NATO Secretary-General Jens Stoltenberg said during a visit to Washington this week that he would convene senior officials from Finland, Sweden and Turkey in Brussels in coming days to discuss the issue.