The New York attorney general is probing whether major Internet providers are charging New Yorkers for faster broadband speeds but fail to deliver the speeds being advertised, according to documents seen by Reuters. The letters, which were sent on Friday to executives at Verizon Communications, Cablevision Systems and Time Warner Cable, ask each company to provide copies of all the disclosures they have made to customers, as well as copies of any testing they may have done to study their Internet speeds.

Time Warner Cable and Cablevision plan to provide performance information to the Attorney General. Verizon has not provided any comment, saying it had not yet seen the letter.

The probe by the attorney general is focused on contractual deals that Internet service providers strike with other networks for the mutual exchange of data.

In the letters, the office says it is concerned that customers paying a premium for higher speeds may be experiencing a disruption in their service thanks to technical problems and business disputes over the interconnection agreements.