The security concerns raised by Turkey in its opposition to Finnish and Swedish bids for NATO membership are legitimate, NATO Secretary General Jens Stoltenberg said Sunday during a visit to Finland, Reuters reported.

Sweden and Finland applied to join a Western defense alliance last month in response to Russia's invasion of Ukraine. But they have faced opposition from Turkey, which has accused them of supporting and harboring Kurdish fighters and other groups it considers terrorists.

Stoltenberg noted that Turkey is a key ally for the alliance due to its strategic location on the Black Sea between Europe and the Middle East, and cited the support it provided to Ukraine after Russia sent troops to the neighboring country on February 24.

Stoltenberg and Niinistö said that talks with Turkey would continue.