NEW YORK — Anonymous telephone threats against commercial airliners, possibly from the same source, caused a scare Monday involving four international flights at airports in New York and New Jersey.

Authorities said the threats did not appear to be credible. They described searches done on three of the jets as a precaution.

U.S. military jets escorted an Air France flight into New York City after someone claimed a chemical weapon was aboard the aircraft, the FBI said.

A Saudi Arabian Airlines flight arriving at Kennedy also was being checked out because of another threat, authorities said.

A third threat was made against an American Airlines jet flying from Birmingham, England, to Kennedy while it was still in the air, said airline spokesman Kent Powell. Authorities initially told the pilot to land and taxi to a remote area away from the terminal but later radioed that the threat was not credible and cleared the plane to go to the terminal, Powell said.

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