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.
Pakistani Foreign Minister Khursheed Kasuri said travel would be granted by an "entry permit system" - rather than a passport - once the identities of travellers are verified.
On Saturday evening, I called Delta to make sure they would accept my Nexus card for re-entry into the United States and was told that the requirements showed that a passport was needed.