In the group photo, UK Prime Minister Keir Starmer stood to Erdoğan's right, and Swedish Prime Minister Ulf Kristersson to his left.
After the photo session, President Erdoğan exchanged handshakes and brief talks with US President Donald Trump and Spanish Prime Minister Pedro Sanchez.
The leaders' session then began behind closed doors. Erdoğan is expected to deliver messages at the summit amid ongoing developments in the Middle East and will hold bilateral meetings.