US magazine Newsweek has changed its policy on using unnamed sources, a week after it was forced to retract a report blamed for riots in Muslim countries.
Newsweek has been accused of damaging the US image
The magazine says that in future anonymous sources will only be used with the approval of top editors.
Newsweek's editor-in-chief apologised for the retracted article that claimed the Koran had been desecrated by interrogators at Guantanamo Bay.
Anti-US riots in Afghanistan following the publication left at least 15 dead.
The White House said the 9 May report - in which it was said the Koran had been flushed down the toilet - had done "lasting damage" to the country's image.
Newsweek retracted the report last week saying its "knowledgeable US government source" was not sure where he had read the allegation.
"The cryptic phrase 'sources said' will never again be the sole attribution for a story in Newsweek," Chairman and Editor-in-Chief Richard Smith wrote in this week's edition.
From now on, only top editors will have the authority to allow the use of unnamed sources in Newsweek reports, he said.
"We got an important story wrong, and honour requires us to admit our mistake and redouble our efforts to make sure that nothing like this ever happens again."
In his letter to readers, Smith also apologised to readers and to anyone "affected by violence that may have been related to what we published".
Protests against the US and Newsweek spread across the Muslim world after publication of the report.
A number of Islamic leaders have since rejected Newsweek's retraction and called for more demonstrations.