SAN FRANCISCO (CBS SF) — Human rights advocates protesting at San Francisco International Airport say a Filipino activist visiting the U.S. for a speaking tour was detained on arrival and is scheduled to be removed from the country later Wednesday.

Jerome Aladdin Succor Aba already had a visa when he boarded his flight, which was scheduled to arrive at SFO around 8 p.m. Tuesday, according to Terry Valen, a spokesman for the International Coalition for Human Rights in the Philippines.

There were people waiting for Aba at the airport.

“We were going to welcome him, feed him, make sure he’s OK and send him off in the morning,” Valen said.

But that didn’t happen. The plane was delayed about 25 minutes. Two hours later, they still hadn’t heard from Aba.

Then around 7 a.m. Wednesday, Aba left a voicemail saying he’d been denied entry to the U.S., and would be removed sometime today, according to Valen.

Sources within U.S. Customs and Border Protection who asked to remain anonymous confirmed that Aba’s application to enter the country was denied due to an unspecified problem with his visa — which is relatively common — and that foreign nationals do not typically have access to an attorney until after they’ve been allowed entry.

As of 2 p.m. Wednesday, Aba was being held in a secured area of the airport with access to food, water and a restroom while he waits for the next available seat on a flight back to the Philippines.

Meanwhile, activists with an amplified sound system are gathering outside the Customs and Border Protection offices at SFO demanding that Aba be allowed to enter the country and consult with legal representation from the National Lawyers Guild.

Valen says Aba’s here to raise awareness about a humanitarian crisis unfolding in the Phillipines, where he said an estimated 20,000 people have died under the “brutal regime” of President Rodrigo Duterte.

The itinerary includes meetings with religious and government officials, including members of the U.S. Senate and House of Representatives, according to Valen.

“These are all meetings scheduled already,” Valen said. “He should be on his way there.”

U.S. Customs and Border Protection does not consider country of origin or human rights activism to be determining factors for admissibility, according to a statement issued today by agency spokesman Jaime Ruiz, but the agency is prohibited from discussing specific cases.

Generally speaking, applicants for entry bear the burden of proof to establish their eligibility under federal law. Specific grounds for denying an application can include health problems, criminal history, security concerns, labor documentation, prior immigration violations, documentation problems and other miscellaneous grounds, according to Ruiz.

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