Police intervened to remove some symbols that are banned in Germany, but made no arrests.

Ocalan's Kurdistan Workers' Party (PKK) is considered a terrorist group by most Western countries, and public displays of some of its symbols is illegal in Germany.

The Cologne protesters marched calmly, with thousands of flags showing Ocalan's mustachioed image, which is legal.

The marchers demanded the release of the 74-year-old former guerrilla, who has been held in an island prison near Istanbul ever since Turkish security agents seized him in Kenya in 1999 and has spent much of that time in isolation.

"He is the greatest revolutionary of the 21st century because with his philosophy and his ideology he provides the opportunity to change our societies, and not just in Kurdistan," said Virginia, a 25-year-old teacher.

"We are here for the freedom of Ocalan, and freedom for Kurdistan's people," said Sakir, a 50-year-old entrepreneur.

Ocalan's entourage has had no contact with him since March 2021 and his last meeting with his lawyers was in 2019.

Despite his isolation, he continues to personify the Kurdish national movement for many of his followers, including in the diaspora, who refer to him simply as "Apo", or "uncle" in Kurdish.

The conflict between the PKK and the Turkish state has left 40,000 dead since 1984.