"What needs to be done is clear: they have to stop allowing PKK outlets, activities, organisations, individuals and other types of presence to...exist in those countries," Türkiye's presidential spokesperson Ibrahim Kalin says.
Türkiye has not shut the door to Sweden and Finland joining NATO but wants negotiations with the Nordic countries and a clampdown on terrorist activities especially in Stockholm, a senior Turkish official said.
"We are not closing the door. But we are basically raising this issue as a matter of national security for Türkiye," the country's presidential spokesperson Ibrahim Kalin told Reuters in an interview in Istanbul on Saturday.
Kalin said PKK - designated a terrorist organisation by Türkiye, the United States and the European Union - was fund-raising and recruiting in Europe and its presence is "strong and open and acknowledged" in Sweden in particular.
"What needs to be done is clear: they have to stop allowing PKK outlets, activities, organisations, individuals and other types of presence to...exist in those countries," Kalin said.
"NATO membership is always a process. We will see how things go. But this is the first point that we want to bring to the attention of all the allies as well as to Swedish authorities," he added.
"Of course we want to have a discussion, a negotiation with Swedish counterparts."
Under NATO rules, any decision on enlargement must be made “by unanimous agreement,” effectively giving Türkiye the power to veto any new members.
Türkiye's security concerns
Sweden and its closest military partner, Finland, have until now remained outside NATO, which was founded in 1949 to counter the Soviet Union in the Cold War.
The two countries are wary of antagonising their large neighbour but their security concerns have increased since Russia's incursion into Ukraine on Feb. 24.
Stockholm is widely expected to follow Helsinki's lead and could apply for entry to the 30-nation military alliance as early as Monday.
For years, Türkiye has criticised Sweden and other European countries for their handling of terrorist organisations, including PKK and the Fetullah Terrorist Organization (FETO).
"If they (Finland and Sweden) have a public concerned about their own national security, we have a public that is equally concerned about our own security," he said.
"We have to see this from a mutual point of view."
Kalin said Russia's sharp criticism of Finland and Sweden over their plans was not a factor in Türkiye's position.