When Nigerian lawyer Obioma Adesewa Okonkwo was booked to speak at the RightsCon conference in Costa Rica, she submitted her visa application several months in advance.

As the date approached with no sign of her travel documents being granted, she felt she had no choice but to cancel her trip and contact organizers at the advocacy group Access Now to arrange to join online instead.

Over 300 participants could not attend the digital rights conference in person due to visa issues, Access Now said in a statement.

Kenyan Nanjala Nyabola, a board member at Access Now, said many Black and brown participants had been picked out and detained by Costa Rican border agents for periods of up to three hours. Some were later deported, she wrote on Twitter.

Anger over their treatment has reignited debate about unequal visa and border regimes that limit Global South nationals’ participation in international conferences tackling issues from climate change to economic systems and conflicts.

"If you have a summit that is global, then you have to consider that there are people coming from countries who are regularly denied visas," said Okonkwo, a legal officer at Media Rights Agenda, which defends freedom of expression in Nigeria.

"I really wanted to learn from digital rights advocates from other continents ... I was shut out from participating in those kinds of discussions."

She said her visa application was eventually rejected.

Access Now, a global organization headquartered in New York, said authorities in Costa Rica had agreed to offer visas on arrival in the country for conference attendees, but border authorities did not uphold the arrangement.

Costa Rica’s embassy in the U.S. referred in a statement to comments made by Foreign Minister Arnoldo Andre Tinoco about the conference.

"It has not been the government of Costa Rica that has prevented these 300 people from entering, but rather they have failed to comply with the minimum requirements to enter the country," he said in a video statement last month.

Conference organizers apologized to all those impacted and pledged to learn and make changes as a result.

"We have a responsibility to ensure that participants are seen and that their voices matter in these spaces," said Nikki Gladstone, RightsCon director, in emailed comments to the Thomson Reuters Foundation.

"It’s our responsibility to anticipate and help mitigate the barriers participants will face."

She said the event is held in different countries each year in an effort to be more accessible, and they chose Costa Rica because they had never had the summit in Central America before.

‘Visa justice’ fights

Critics say visa rules that are stricter for citizens of poorer nations are a significant factor limiting the participation of people from developing countries in major conferences.

Ugandan climate activist Hamira Kobusingye said she often needs letters of recommendation to apply for visas to attend summits – a step not required of most Global North travelers.

Despite her efforts, she said she was denied visas to attend the Bonn Climate Change Conference in Germany in June and the U.N. 2023 Water Conference in New York.

"My colleagues all over the continent were denied visas," she said, adding that they were being distracted from their campaigning work by "visa justice" battles.

Kobusingye said she was told her applications did not meet the criteria for a visa.

A U.S. state department spokesperson said it "takes seriously its obligations as a host country of the U.N."

"Whenever an individual applies for a U.S. visa, a consular officer reviews the facts of the case and determines whether the applicant is eligible for that visa based on U.S. law," the spokesperson said in emailed comments.

Neither the German foreign office nor its embassy in Uganda responded to requests for comment.

Kobusingye said restricting access to grassroots campaigners meant major decisions could be made without much input from the people who are most affected.

Africa has been hit disproportionately hard by the fallout from climate change, while international efforts to secure funds for adaptation and recovery for heavily affected developing nations have fallen short.

"It seems like the Global North is trying to find solutions for the climate crisis without the people who are most affected," said Kobusingye.

"They can push through what they want because they have very little resistance."

In 2021, after Black Lives Matter protests in many countries prompted widespread discussions over inclusion, the COP26 U.N. climate summit was criticized for lack of diversity, with the hashtag #cop26sowhite trending on Twitter.

The U.N. climate change body UNFCCC, which organizes the Bonn and COP summits, did not immediately respond to requests for comment.

Ahmed Ogwell Ouma, acting director of the Africa Centers for Disease Control and Prevention, said he struggled to enter Germany for a world health summit last year because of mistreatment by border staff who suspected he wanted to stay on illegally.

"My attendance of the @WorldHealthSmt is now in doubt. I’m happier & safer back home in Africa. They invite you, then mistreat you," he wrote on Twitter.

Ouma was ultimately granted entry, and the German health minister later tweeted that officials were looking into what had gone wrong at the airport.

Not in the room

Campaigners and policy analysts said summit organizers should be mindful of visa policies when selecting host countries.

Okonkwo said organizers should have conferences in visa-friendly countries that are not discriminatory towards people from poorer nations.

In an open letter with charities and civil society groups, Access Now urged governments to adopt "flexible and generous" visa approval policies for human rights defenders, activists and journalists.

Enabling Global South participants to be physically present at high-level talks was critical to ensure decisions are as representative as possible, said Kathryn Nwajiaku-Dahou, director of the Politics and Governance program at ODI, a global think-tank based in Britain.

"It’s where the real political work takes place. It’s what happens in the corridors; it’s the informal mingling. That’s where powerful relationships get struck," she said.

"So, if you’re not in the room, you’re not in the room."