US government agencies are investigating at least 11 threats against specific international commercial flights on Monday afternoon, apparently phoned in to police by the same person, US officials said on Tuesday.

One flight, Air France flight 22 from Paris was escorted by two US F-15 fighter jets to New York's John F. Kennedy International Airport after authorities received a threat, said the officials, who asked not to be identified.

The plane landed safely and was cleared with no incidents or hazards reported by passengers or crew, said J. Peter Donald, an FBI spokesman.

Threats were also made to flights both to and from US airports, including Newark and Atlanta, as well as flights between other foreign cities in Europe, North and South America and the Middle East, one official said.

Officials said they believed all of the threats were phoned in to local police departments by the same individual, but added the caller's identity and motive were not yet known.

No evidence of explosives was found, and officials said the threats were disruptive and wasted law enforcement resources.

Among the theories under investigation were that the threats may have been the work of a troublemaker or mentally disturbed individual or an effort by an individual or group to test how US agencies respond to such threats, officials said.

US aviation security authorities receive and investigate an average of one such threat per day, one of the officials said. – Reuters