NATO Secretary-General Jens Stoltenberg acknowledged Turkey's security concerns over Sweden and Finland's membership bids for the bloc, as he highlighted the importance of Turkey to the alliance.

"I also recognize the importance of addressing the concerns that Turkey has raised," Stoltenberg told the World Economic Forum in Davos, Switzerland.

He said Turkey "is an important ally" that has played a "key role" in the fight against Daesh and has a "strategic geographic location," which "is important for the whole Alliance."

Stoltenberg pointed out that "no other NATO ally has suffered more terrorist attacks than Turkey."

"We have to sit down and find a way forward," he said.

Sweden and Finland formally applied to join NATO last week, a decision spurred by Russia's war on Ukraine, which began in February.

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 such as the PKK/YPG. The accession requires unanimous approval from all 30 NATO member states.

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.