The New York attorney general subpoenaed more than a dozen telecommunications trade groups, lobbying contractors and Washington advocacy organizations on Tuesday, seeking to determine whether the groups submitted millions of fraudulent public comments to sway a critical federal decision on internet regulation, according to a person with knowledge of the investigation.

Some of the groups played a highly public role in last year’s battle, when the Federal Communications Commission voted to revoke rules that classified internet service providers as public utilities. The regulations, made under President Barack Obama, were meant to guarantee full and equal access to the internet, a principle known as net neutrality. The telecommunications industry bitterly opposed them and enthusiastically backed a repeal under President Trump.

The attorney general, Barbara D. Underwood, is investigating the source of more than 22 million public comments submitted to the F.C.C. during the battle over the regulations. Millions of comments were provided using temporary or duplicate email addresses, while others recycled identical phrases. Seven popular comments, repeated verbatim, accounted for millions more.

The noise from the fake or orchestrated comments appears to have broadly favored the telecommunications industry: One recent study, by a researcher at Stanford, found that virtually all of the unique comments submitted to the F.C.C. — the ones most likely to be bona fide — opposed repeal.