A security alert involving the singer who used to be known as Cat Stevens has forced a London-to-Washington flight to be diverted to another US airport.
The plane was already in the air when US officials identified that the singer, whose name is now Yusuf Islam, was on one of their "watch lists".
United Airlines Flight 919 was diverted 600 miles (1000km), landing in Maine.
After an interview, the singer - who converted to Islam in 1977 - was denied entry into the US.
Transportation Security Administration (TSA) officials said the access was denied "on national security grounds", without giving any further details.