New York (CNN) -- The New York Police Department executed search warrants Tuesday at some offices of The New York Times, The New York Daily News, The New York Post and El Diario newspapers and at a labor union, with authorities saying they were conducting investigations into "business activity."
Local media reports categorized the action as searches of the newspapers' circulation offices in connection with an investigation of the Newspaper and Mail Deliverers' Union of New York.
Deputy Police Commissioner Paul J. Browne confirmed the searches to CNN but neither he nor other city officials would elaborate on the investigation or discuss Tuesday's actions.
District Attorney Robert Morgenthau said in a statement, "Today police officers executed search warrants obtained by the District Attorney's office at locations including the offices of a number of print media organizations and a labor union.
"The investigation solely concerns business activity and practice and is completely unrelated to the content of any publication. The investigation is continuing. We can offer no further information at this time."
Reached by phone, the Newspaper and Mail Deliverers' Union's secretary-treasurer, Steven Goldstein, said that the union was not commenting.
Suzi Halpin, a spokesperson for The New York Post, declined to comment. Calls made to The New York Daily News and El Diario were not returned.
Diane McNulty, a spokeswoman for The New York Times, said that police executed a warrant to search the office of an employee at College Point in the Queens section of New York, but that, "The New York Times Company is not a target of the investigation."