A leading House Democrat is demanding information from the country’s biggest cellphone companies about their role in helping local police departments conduct surveillance and tracking of suspects and others in criminal investigations.

Representative Edward J. Markey of Massachusetts, the co-chairman of the Congressional Bipartisan Privacy Caucus, said in a letter sent Wednesday to eight major wireless carriers that he was “deeply concerned” that routine tracking of cellphone use by law enforcement officials in many departments “may violate the privacy rights of Americans.”

In his letter, Mr. Markey sought data from the cellphone carriers on the number of requests for help they have received from law enforcement officials in cell tracking and surveillance operations, their policies on whether they require the authorities to secure court warrants, the use of cellphone surveillance in nonemergencies, the fees they charge the police and other information.

His letter was prompted by an April 1 article in The New York Times on the routine use of cellphone surveillance by local police departments, even in nonemergency situations. Mr. Markey’s office provided a copy of his letter to The Times.

The move by Mr. Markey puts the cellphone companies in the middle of a protracted public debate over the balance between civil liberties safeguards and the authorities’ use of surveillance technology. The issue has received renewed public attention recently as a result of a Supreme Court ruling in January finding that police use of a GPS device on a drug suspect’s car without a warrant violated his Fourth Amendment rights.

CTIA, the wireless industry trade association, said it had no comment on the Congressional request...