Chinese artist Ai Weiwei outside his studio in Beijing after his release on bail in June 2011. Photograph: Peter Parks/AFP/Getty Images

The dissident Chinese artist Ai Weiwei, who shot to worldwide prominence this April when he was imprisoned by the Chinese authorities for 81 days for what were described as "economic crimes", has been named the most powerful figure in the art world by Art Review magazine in its annual art "power 100 list".

Mark Rappolt, editor of the magazine, said that Ai – who was No 13 on the list last year – had reminded the art world of its wider political role, as an agent of protest outside the sometimes inward-looking domain of galleries and museums.

"His activism has been a reminder of how art can reach out to a bigger audience and connect with the real world," he said. "Institutions, while they are really important, can be great tombs."

The highest-ranking British figure is Julia Peyton-Jones, co-director of the Serpentine Gallery. She shares the No 2 slot with her colleague, Swiss curator Hans-Ulrich Obrist.

The Serpentine, Rappolt said, was "really growing into something freewheeling, and not limited by its modest space".