An Emirates plane flying to New York from Greece was forced to return to the Athens International Airport after a security alert, police sources said on Thursday.

Greek authorities were tipped off by U.S. about a “suspicious” passenger on the plane, according to police sources and local media.

Just after 2000 GMT the plane, escorted by two fighter jets, landed back at the Eleftherios Venizelos airport in Athens for security checks, the sources said.

Earlier on Thursday, another Emirates flight to Dubai was not allowed to take off from Eleftherios Venizelos and all passengers were thoroughly checked also for security concerns but nothing suspicious was found, police sources added.