The Reuters news agency said Monday it has cut its ties with a Beirut-based freelance photographer who it found had manipulated two photographs from the ongoing fighting in Lebanon. It also removed all 920 pictures by the photographer from its database.

The agency said that as a result of the discovery it has put in place tighter editing procedures for images from the Middle East, requiring that all such photos be reviewed by the top photo editors at Reuters' global photo desk.

One of the photographs by Adnan Hajj showed the aftermath of an Israeli air strike on an area of suburban Beirut. It had been manipulated using Photoshop software to show more and darker smoke rising from the buildings.

Reuters cut its relationship with Hajj on Sunday after reviewing that photo, and on Monday found that he had also manipulated a second photograph, showing an Israeli jet fighter over southern Lebanon and dated Aug. 2. In that photo, Hajj changed the image to show three flares being dropped by the plane, instead of just one, the agency said.

"There is no graver breach of Reuters standards for our photographers than the deliberate manipulation of an image,'' Tom Szlukovenyi, global photo editor of Reuters, said in a statement from London, where the company has its headquarters. "Reuters has zero tolerance for any doctoring of pictures and constantly reminds its photographers, both staff and freelance, of this strict and unalterable policy.''

Hajj worked for Reuters as a non-staff contributing photographer from 1993 until 2003 and again since April 2005.

According to Reuters spokeswoman Moira Whittle, Hajj denied deliberately attempting to manipulate the image. He said he was trying to remove dust marks and made mistakes because of bad lighting conditions, she said Sunday.

Hajj also worked as a freelancer for The Associated Press from 2003-2005. Santiago Lyon, AP's director of photography, said the AP was reviewing all 193 of his images in its photo archives to verify their authenticity.

Also on Monday, the AP recalled a photo that it had transmitted Sunday night of a worker in Alaska examining an oil pipeline. In that photo, the worker appeared to have four hands, and there were other elements such as a section of pipe that appeared to have a double image.

Lyon said the distortions were unintentional and resulted from careless use by the photographer of a software feature in Photoshop called a "cloning tool.'' The photographer had used the feature in an attempt to clear up a glitch in the picture caused by a dirty sensor, the part of a digital camera that records the image. AP's ethical guidelines permit use of "cloning'' in limited circumstances to clean up dirt or scratches from an image.

Lyon said the error was not caught by either the photographer or the editing desk before it was transmitted on the AP's photo service. He said the company was reviewing disciplinary actions against the photographer and other parties involved.

Last month, The Charlotte Observer said it had terminated one of its photographers, Patrick Schneider, after finding that he had altered the colours in a photo of a firefighter on a ladder.

Kenny Irby, visual journalism group leader at The Poynter Institute for Media Studies in St. Petersburg, Fla., said all three instances show that news organizations need to be more careful in how they handle images.

"There has to be an editing component that ensures the accuracy of the content,'' Irby said. "It's not just the photographer that should be examined, but the overall process of the news organization that must be held accountable.''