One of Unesco’s chiefs has said she will no longer host any international conferences in the UK because of the Home Office’s “inept”, “embarrassing” and “discriminatory” visitor visa system.

Alison Phipps, the Unesco chair in refugee integration, has accused the government of operating in effect a “secret travel ban” by refusing visitor visas to academics – particularly those from Middle Eastern and African countries – even when they have full sponsorship to visit the UK and are visiting to take part in government-funded projects.

Another academic, Elena Fiddian-Qasmiyeh, a professor of migration and refugee studies at University College London, spoke of the frustration of inviting academics to attend a parliamentary event in March, which was co-sponsored by the House of Commons’ international development committee, only for most visas to be refused.

Mary Ryan, a research manager and the international development coordinator at the Glasgow Centre for International Development, has said there is “deep-seated concern” for the ability of UK research institutions to be globally relevant given the “perceived obstructive nature of visa processes”.

Phipps said: “I have taken a policy decision with my work as Unesco chair and with my project portfolio not to host any international conferences in the UK. It is a waste of taxpayers’ money and given the irresponsibility and erratic nature of UKVI decision-making, it’s the number one item on my risk register and we cannot, with any integrity, allow that kind of finance risks to the projects.”

Phipps is particularly frustrated by the refusal of the Home Office to issue visitor visas to academics taking part in the government’s own Global Challenges Research Fund – a five-year, £1.5bn fund that uses UK aid money for research on intractable global challenges.

“The fund’s purpose is to hire and pay overseas academics to work with the UK on a range of government-funded projects,” said Phipps. “But even though we’re using the government’s money for exactly the purpose we’ve been given it, academics we sponsor are turned down with no appeal rights.”

Temitayo Olofinlua, an academic, applied for a visa to come to Edinburgh from Nigeria for an European Conference on African Studies conference on 4 April. Despite submitting evidence of full sponsorship for her trip – as well as evidence of ties to her home, namely that she is married with children and a job – her application was refused.

Her case worker told her she had been refused because “I am not satisfied that you are genuinely seeking entry as a visitor … or that you intend to leave the UK at the end of your visit.”

Olofinlua’s refusal was eventually overturned and she is in Edinburgh, attending the conference. But, she said: “It’s time to abandon the UK as host for international African Studies conferences. The organisers did everything to make this an inclusive event. But hostile Home Office policy has dampened this. Other countries require you to declare if you have ever been denied an entry visa.”

“Going through the experience has been tortuous,” added Olofinlua, who frequently travels and always kept to visa conditions. “I lost money. I lost valuable time, thanks to the tedious process of applying and re-applying, making the overnight visit to Lagos then standing hours in line.”

Other reasons for refusing visitor visas include fully funded academics told they could not support themselves while here. Others with children or important jobs in their home countries – such as Rev Rola Sleiman, the first woman to be ordained in the Middle East – being told their applications failed because, as with Olofinlua, it was thought they would not return home.

Frustrated by the frequency with which visas they applied for were refused, the Glasgow Centre for International Development recently asked its partners for information on visa denials for researchers from low and middle income countries (LMIC) coming to visit UK institutions.

They received 31 instances of visitor visas for academics being denied since 2017. “All visits were fully funded by grants or other funds; none relied on the personal funds of the visitor, and all were directly linked to ongoing research activities,” said Ryan.

“In each case, the denials impact the relationships our institutions have with colleagues in LMIC institutions,” said Ryan. “Several respondents commented on the embarrassing nature of having to share financial details with colleagues, the damage to the research partnerships of not being able to meet and the personal toll of managing international relationships with colleagues in the face of institutional obstructions. In several cases, there were significant financial losses due to flight cancellations and re-bookings,” said Ryan.

A Home Office spokesperson said: “All immigration applications are considered on their individual merits and on the basis of the evidence available, in line with the immigration rules.

“We welcome international academics and recognise their contribution to the UK’s world-leading education sector.”