A Muslim teacher from Neath Port Talbot has been denied entry to the United States while on a school trip.
Juhel Miah had flown to Reykjavik, Iceland, with the party from Llangatwg Community before boarding an onward flight to New York.
But before the plane took off on 16 February, he was escorted off by security staff.
BBC Wales has asked the US Embassy in London to comment.
Neath Port Talbot council has written to the US Embassy to "express its dismay" at the treatment of Miah, who the local authority said had a valid visa to travel.
The school trip continued as planned but Miah's removal left pupils and colleagues "shocked and distressed," a spokesman said.
"We are appalled by the treatment of Miah and are demanding an explanation.
"The matter has also been raised with our local MP."
Miah, who teaches maths at the 700-pupil school, was also denied access to the US Embassy in Reykjavik, the spokesman added.
"No satisfactory reason has been provided for refusing entry to the United States - either at the airport in Iceland or subsequently at the embassy.
"Understandably he feels belittled and upset at what appears to be an unjustified act of discrimination."
On 27 January, US President Donald Trump signed an executive order halting all refugee admissions and temporarily barring people from seven Muslim-majority countries, sparking numerous protests and legal challenges.
A week later a federal judge in Seattle suspended it nationwide - a ruling which was later upheld at an appeals court hearing in San Francisco.
Trump is now considering a revised plan.
Abdul-Azim Ahmed, assistant secretary general of the Muslim Council of Wales, said he was "deeply troubled" by the incident.
"What we do know is quite troubling and in the context of a school trip and the children being left with one less teacher because of this," he said.
"This is the latest in a series of incidents where Muslims have been denied entry to the US which date before even Trump was elected."
The school party returned to the UK on Monday after the week-long trip.