The official says the offices of The New York Times, the New York Post, El Diario and the Daily News of New York were raided Tuesday. The official spoke to The Associated Press on the condition of anonymity because the investigation is ongoing.
The official says the newspaper delivery system around the city is under investigation and the news organizations are not involved.
The 1,600-member union that delivers papers was previously accused by the Manhattan district attorney's office of being run by the mob.
Calls to the four newspapers weren't immediately returned Tuesday.