An Iranian cancer researcher arriving in the U.S. to start work at a prominent Boston hospital has been detained at Logan International Airport.

Boston Children's Hospital said Tuesday that Mohsen Dehnavi is a visiting scholar with a J-1 visa issued in May but was prevented from entering the country with his wife and three young children this week for reasons that still remain unclear.

The hospital said in a statement that the family could be deported, but it hoped they would be allowed to enter the U.S.

A U.S. Customs and Border Patrol spokeswoman declined to comment, citing privacy laws that prohibit the agency from discussing individual cases.

The Supreme Court recently ruled that President Donald Trump's administration could largely enforce its travel ban on six Muslim-majority countries, including Iran.