The siege of Comcast has expanded.

Attorney General Andrew Cuomo of New York subpoenaed records from the company, the nation's largest cable-TV operator. His office declined to say exactly what information it was seeking.

Dow Jones Newswires, citing unnamed sources, and the Associated Press said that the probe relates to Comcast's practice of slowing down or blocking the delivery of some internet content over its cable network. The company says it is engaging only in prudent network management, but critics have accused it of trying to hobble rivals in the video-on-demand business.

The controversy has already attracted the attention of both Congress and the Federal Communications Commission, which have opened separate investigations of the company's practice.

It has also prompted some customers to sue, and led to the creation of an ad hoc coalition of academics and other free-speech advocates to push regulators to prevent cable operators and phone companies from slowing or blocking the delivery of targeted internet content over their systems.

Cuomo's office has joined the assault even though only a few New Yorkers are Comcast customers—less than 1 percent of all cable subscribers in the state.

Comcast has also sparked fury in the tech community for having paid people to show up to a public hearing that the F.C.C. held at Harvard on Monday. The company said it did so to reserve space for its employees to attend, but critics accused Comcast of trying to keep opponents out while creating the false impression that it had broad support.

"We did pay some individuals to stand in line and hold seats for Comcast employees," Comcast spokesman Charlie Douglas told the blog Ars Technica. "It's a common practice in Washington, D.C."