An academic's visa rejection is "damaging" to the UK's reputation, organisers of an international Egyptology conference have said.
Gehad Ali, curator at the Egyptian Museum in Cairo, was due to present a paper at Swansea University this week.
Organisers say Ms Ali's visa was rejected because she didn't have enough money to support herself during her visit.
The Home Office said applicants needed to show they met immigration rules.
Swansea University said Ms Ali's visa rejection was "disappointing".
Initially, two other Egyptology experts had been refused visas alongside Ms Ali, however the pair have since been granted them after reapplying.
The international conference, called Beating Barriers, began on Tuesday.
Gabriele Pieke, president of the Comité Internationale pour L-Egyptologie (CIPEG) said she could not understand the decision to reject Ms Ali's visa application as her trip to the conference was fully funded by CIPEG.
Ms Pieke's organisation and its governing body - the International Council of Museums - have condemned the decision not to grant Ms Ali a visa.
"This jeopardises what we stand for, an international exchange of ideas," Ms Pieke said.
"To not let a respected academic come her because she's too poor? It's really shocking."
The International Council of Museums also said it was concerned other international events might be affected by visa restrictions in the future.
"This policy will not only deter international organisations from holding their conferences and meetings in the United Kingdom if members from Africa, Asia or Latin America cannot participate; it will also hinder the development of the scientific and professional community in the UK," the organisation said.
Elham Salah, head of the museum sector in Egypt's Ministry of Antiquity, said Ms Ali will now have to make her presentation via a video conference.
"She is very sad and it's not the first time academics from Egypt have faced visa problems," Ms Salah said.
The Swansea West MP Geraint Davies called the UK Immigration policy "disgraceful" and said it would "isolate UK academia from the world."
The Home Office said the onus was on the applicant to demonstrate that they satisfied the immigration rules.
"All UK visa applications are considered on their individual merits and in line with UK immigration rules and guidance," a spokesperson said.
"In addition to any support provided by a sponsor, decision makers will take account of an applicant's own personal and financial circumstances in assessing whether the application meets the requirements of the immigration rules."