Sweden said it is investigating the social media posts showing the YPG/PKK terrorist group's so-called flag and its convicted ringleader, Abdullah Öcalan, reflected onto landmark buildings in Stockholm.

"Messages and images that we have reason to believe are manipulated have been circulating on social media, asserting that Sweden supports PKK. Relevant measures have been taken," the ministry said in a statement.

"This is a deliberate and malicious influence campaign with the clear aim of obstructing Sweden's accession to NATO," it said.

Sweden has denounced the PKK terrorist group and condemns terrorism in all its forms, it noted.

Foreign Minister Ann Linde has never expressed any support for the terrorist group and strongly rejects the manipulated video and the PKK, it added.

YPG/PKK-linked social media accounts shared images showing the terrorist groups's so-called flag and its leader's picture projected onto the historic City Hall in Stockholm.

The accounts also posted the images on the wall of the Globen Avicii Arena Sports Hall.

Turkey's Ambassador to Stockholm Hakkı Emre Yunt told Anadolu Agency (AA) that he confirmed the incident during his morning meeting with the diplomatic police.

"Police confirmed the image on the Globen Avicii Arena Sports Hall in Stockholm. Police also stated that the image projected on the historic city hall in Stockholm is most likely correct," said Yunt.

Sweden and Finland formally applied to join NATO last month – a decision spurred by Russia's war on Ukraine, which began Feb. 24.

But Turkey, a longstanding member of the alliance, has voiced objections to the membership bids, criticizing the countries for tolerating and even supporting terrorist groups.

In its more than 40-year terror campaign against Turkey, the PKK – listed as a terrorist organization by Turkey, the United States and the European Union – has been responsible for the deaths of over 40,000 people. The YPG/PKK is PKK's Syrian offshoot.