Over sixty curators, critics, and museum directors based in cities ranging from Rotterdam to Dakar have now signed a letter in support of Andrew Ross, Ashok Sukumaran, and Walid Raad, who were recently denied entry to the United Arab Emirates. Ross, an NYU professor, was turned away in March when he tried to check in at an airport on his way to the UAE, while Raad was detained and then sent home while trying to go to the March Meetings hosted by the Sharjah Biennial and Sukumaran was denied a visa despite submitting repeated applications.

Though “security” was the reason provided by authorities who denied Raad and Sukamaran entry, this latest letter reads, “It appears that the reason these three members of our global arts and academic community were denied entry to the UAE is their involvement with the Gulf Labor Coalition.”

“We the undersigned oppose the barring of Ashok Sukumaran, Walid Raad and Andrew Ross from the UAE,” reads the letter. “We state that denying artists visas, stopping and deporting them after years of their work in the region, creates a chilling precedent and makes it difficult for arts and academic institutions in the UAE, and those working with the UAE to claim regional dialogue and artistic freedom. We urge your institutions to work with the concerned authorities to lift these bars on their travel.”

The letter—whose signatories include everyone from Achim Borchardt-Hume, director of exhibitions at Tate Modern, London, to Glenn Lowry, director of the Museum of Modern Art in New York, to Sheena Wagstaff, chairman of the department of modern and contemporary art at the Metropolitan Museum in New York—follows on the heels of another recent letter, signed by Sharjah Biennial artists, also in support of Ross, Shukumaran, and Raad.

The latest letter can be read in full here.