A top London university has abruptly pulled out of a conference scheduled to be held on Sunday in the United Arab Emirates.
The London School of Economics (LSE) cited concerns about restrictions that "threatened academic freedom".
The conference was examining the causes of the Arab Spring and its ongoing impact in the region and beyond.
A senior LSE academic told the BBC he had been detained at the airport in Dubai on Friday.
Dr Kristian Coates Ulrichsen, who is the co-director of the Kuwait programme at LSE, said immigration authorities had separated him from his colleagues and confiscated his passport before denying him entry and sending him back to London.
In an earlier statement given to the BBC, the university said:
"The London School of Economics and Political Science has cancelled a conference it was co-hosting with the American University of Sharjah on The Middle East: Transition in the Arab World.
"The decision was made in response to restrictions imposed on the intellectual content of the event that threatened academic freedom."
It did not say who had placed restrictions on the conference but a well-placed source told the BBC pressure had come from "very senior" UAE government officials.
To date LSE has received £5.6m ($8.5m) from the Emirates Foundation, which is funded by the UAE government, but the institution denied that the foundation was involved in placing the restrictions.
But the LSE has been sensitive to criticism about accepting money from Middle East sources since its close links to the former Libyan dictator Muammar Gaddafi and his family were revealed in 2011.
The university was criticised at the time for a "chapter of failures" in its links with the Gaddafi regime.
A report by former Lord Chief Justice Woolf released in November 2011 said that mistakes and errors of judgement had damaged the LSE's reputation.