At least three planes have been searched at Newark Liberty International Airport after anonymous telephone threats were made against international flights arriving at several airports.

Authorities say none of the threats appear credible.

United Airlines spokeswoman Mary Clark says passengers at Newark were removed from a flight after it arrived from Madrid. The plane was being inspected Monday afternoon at a spot away from the terminal.

The FBI in Newark said two other planes also were searched. One was a United flight from Edinburgh, Scotland, and the other was a Delta flight from London.

A series of threats against commercial airliners prompted U.S. military jets to escort an Air France flight into New York's Kennedy Airport after someone claimed a chemical weapon was aboard the aircraft. At least two planes were searched at the airport.