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 sought to sway a critical federal decision on internet regulation last year by submitting millions of fraudulent public comments, 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 Republican-appointed majority on the Federal Communications Commission voted to revoke a regulation issued under President Barack Obama that classified internet service providers as public utilities. The telecommunications industry bitterly opposed the rules — which imposed what supporters call “net neutrality” on internet providers — and enthusiastically backed their repeal under President Trump.

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

The noise thrown up by fake or orchestrated comments appears to have favored the telecommunications industry: One 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.