NEW YORK — Newsweek has announced plans to limit the magazine's use of anonymous sources following a scandal in which one of its stories was blamed for deadly protests in Afghanistan.

In a letter to readers appearing in Monday's edition, Newsweek Chairman and Editor-in-Chief Richard Smith apologized for the original report and said the magazine will raise standards for unnamed sources.

Two of the magazine's top editors will be assigned sole responsibility for approving the use of such sources, and the magazine will stop using the phrase "sources said" to attribute information in stories, Smith said.

"We got an important story wrong, and honor requires us to admit our mistake and redouble our efforts to make sure that nothing like this ever happens again," he wrote.

The disputed May 9 article said U.S. investigators had found evidence that interrogators placed copies of the Qur'an in washrooms and had flushed one down the toilet to get inmates to talk. The magazine's report was blamed for violent protests in Afghanistan, where more than a dozen people died and scores were injured.

Rallies are planned for Friday in Pakistan and other countries to protest the report, with Islamic leaders calling on Pakistan's president, Gen. Pervez Musharraf, abandon his support for President Bush's war against terrorism.

In a note to readers last week, Newsweek Editor Mark Whitaker said the information came from "a knowledgeable U.S. government source," and before the magazine published the item, writers Michael Isikoff and John Barry sought comment from two Defense Department officials.

One declined to respond, and the other challenged another part of the story but did not dispute the Qur'an allegation, Whitaker said.

Whitaker said the magazine's original source later said he could not be sure he read about the alleged Qur'an incident in the report Newsweek cited, and that it might have been in another document.

In the latest issue, the magazine stopped short of requiring that its reporters corroborate sources speaking on condition of anonymity with a second source, but Smith said that editors would work harder to do so.

"When information provided by a source wishing to remain anonymous is essential to a sensitive story — alleging misconduct or reflecting a highly contentious point of view, for example — we pledge a renewed effort to seek a second independent source or other corroborating evidence," Smith said.