NEW YORK (AP) — The Associated Press and video services operated by CBS and NBC have pulled video allegedly taken of a tornado in Nebraska last weekend after questions were raised about its authenticity.

A tornado chaser has claimed that the video was a doctored version of pictures he had taken of a twister that touched down four years ago in Rock, Kansas.

The AP paid another storm chaser, Andy Fabel, $295 for footage of a tornado that briefly touched down last Saturday afternoon near Valentine, Nebraska. The video was sent Sunday to nearly 2,000 Web sites that subscribe to the AP's Online Video Network, and more than 60 large digital customers that buy AP's online content individually.

Yet on Tuesday, a person who asked that his name not be used contacted, the AP and said the supposed Nebraska footage was really video he had taken four years ago. The image was "flipped" to make it seem the tornado was pointed in another direction, and the action sped up. The Nebraska images add power lines and subtracts trees that were in the Kansas pictures.

Upon seeing the video evidence, the AP eliminated Fabel's video from the Online Video Network late on Tuesday and contacted its other customers to urge them not to use it, said Kevin Roach, the AP's acting head of domestic broadcast news operations.

"We never want to mislead people," Roach said. "Based on evidence provided to us, we believe that the video was not authentic."

Fabel did not immediately return an e-mail and message left on his cell phone by the AP. Officials with NBC News Channel and CBS News Path said they had talked to Fabel and he had insisted his pictures were authentic.

Both the NBC and CBS services provide video to the network's affiliates. Both had purchased Fabel's video and sent it out, then took it off their servers on Tuesday after suspicions were raised about its authenticity, representatives said.

"There was enough evidence for us to make it suspect," said Sharon Houston, an executive producer with NBC News Channel.

The AP has purchased tornado video from Fabel three times before, Roach said.