NEW YORK (AFP) - Two customs inspectors at New York's John F. Kennedy airport fell ill Sunday after handling a parcel in a mail center that apparently contained a toxic chemical, local media reported.

The Federal Bureau of Investigation (FBI) confirmed that it dispatched a hazardous response team to screen the two workers and the package for what a spokesman called "possible contaminants."

On its website, the New York Post claimed the parcel had tested positive for a nerve gas known as VX, but police sources told AFP it could be several days before the exact nature of the substance is established.

Local news channel WNBC said the two customs inspectors had recovered from their nausea and declined further medical help. Citing a law enforcement official, the station added that the package may have originated in China.

The incident - which had no impact on any JFK passenger terminal or flight operations - came after a week of heightened concerns in the United States over a potential terrorist attack overseas.