LONDON (Reuters) - Chinese artist Ai Weiwei has been named the art worlds most powerful figure in a new ranking. Contemporary art magazine ArtReview published its 10th annual Power 100 list on Thursday, coinciding with the opening of the Frieze Art Fair in London which attracts many of the worlds top galleries and collectors. Ai, famous for his Birds Nest Olympic Stadium in Beijing and a recent installation at Londons Tate Modern gallery comprising millions of replica porcelain sunflower seeds, was 13th in the ranking last year. Unchanged in second place was Londons Serpentine Gallery co-director Hans Ulrich Obrist, joined by his colleague Julia Peyton-Jones this time around. They are followed by New Yorks Museum of Modern Art director Glenn D. Lowry, and, in fourth down from first last year, U.S. gallery owner Larry Gagosian. Mark Rappolt, editor of ArtReview, said the choice of Ai by a panel of experts was not a political one. Of course its something about political activism that runs through the list this year, he told Reuters. But I think its more about expanding the concept of art thats not really solely contained in the privileged space of museums and galleries. Its about how it engages with the world. Its expanding the possibilities of what you can do with art and as an artist how you can use your voice. Ai, who spent nearly three months in detention, was released in late June after being taken from Beijing airport and held in two secret locations. His family says he was targeted by authorities for his criticism of censorship and Communist Party controls, and Ai has remained largely silent since his detention because, under the conditions of his release, he is not allowed to be interviewed by journalists or use the Internet. Ai is only the second artist to have topped the ArtReview standings after Britains Damien Hirst in 2005 and 2008. Hirst continued to slip further down the whos who list in 2011, moving to 64th from 53rd last year. Top 10 individuals in the world of art 1. Ai Weiwei/China/artist 2. Hans Ulrich Obrist/Switzerland; Julia Peyton-Jones - gallery directors 3. Glenn D. Lowry/United States/ museum director 4. Larry Gagosian/United States/gallerist 5. Anton Vidokle/Russian-born; Julieta Aranda/Mexico; Brian Kuan Wood/United States - partners in art network group e-flux 6. Nicholas Serota/Britain/museum director 7. Cindy Sherman/United States/ photographer 8. Iwan Wirth/Switzerland/gallerist 9. David Zwirner/Germany/gallerist 10. Beatrix Ruf/Germany/curator.