PHILADELPHIA – Comcast Corp., an Internet service provider under investigation for hampering online file-sharing by its subscribers, announced Thursday an about-face in its stance and said it will treat all types of Internet traffic equally.

Comcast said it will collaborate with BitTorrent Inc., the company founded by the creator of the popular BitTorrent file-sharing protocol, to come up with better ways to transport large files over the Internet instead of delaying file transfers.

Since user reports of interference with file-sharing traffic were confirmed by an Associated Press investigation in October, Comcast has been vigorously defending its practices, most recently at a hearing of the Federal Communications Commission in February.

Consumer and “Net Neutrality” advocates have been equally vigorous in their attacks on the company, saying that by secretly blocking some connections between file-sharing computers, Comcast made itself a judge and gatekeeper for the Internet.

They also accused Comcast of stifling delivery of Internet video, an emerging competitor to the core business of the nation’s largest cable operator.

It was not immediately clear what effect the move will have on the FCC’s probe, but Net Neutrality groups remained skeptical.

“This deal is the direct result of public pressure, and the threat of FCC action, against Comcast,” said Marvin Ammori, general counsel of Free Press, a media reform group. “But with Comcast’s history of broken promises and record of deception, we can’t just take their word that the Internet is now in safe hands.”

Shares in Comcast fell 13 cents to $19.58 Thursday.

Associated Press writers Barbara Ortutay and Peter Svensson contributed to this report.