Terror leader Usama bin Laden plans to address Americans on the sixth anniversary of the Sept. 11 attacks in a new video, according to a terror monitoring group.

SITE Intelligence Group said an Internet announcement of the plan included a photo of the al-Qaeda leader from the upcoming video — his beard, which in previous messages had been streaked with gray, was entirely dark.

A senior U.S. official with knowledge of intelligence affairs tells FOX News that "no one should be surprised to get a message from Al-Qaeda around this time."

The official could not confirm or deny the authenticity of the images released, but he said "it's not exactly clear at this point" if the message will be authentic. The official also pointed out that previous messages were later proved to be older footage.

Another group that monitors Islamic Web sites said the video could come within the next 72 hours, or by Sunday. The prediction by Intelcenter, based in Alexandria, Va., would make the release of the video before the sixth anniversary of the terrorist attacks in New York, Washington, D.C., and Pennsylvania.

Rita Katz, director of the Washington-based SITE Institute, said bin Laden's beard appeared to have been dyed, which she said is a popular practice in the Middle East.

"I think it works for their benefit that he looks young, he looks healthy," Katz said of the new image.

The last bin Laden video was in October 2004, shortly before the U.S. presidential elections.

Meanwhile, federal counterterrorism officials are analyzing a posting on an Islamic forum Web site that warns of "a special gift" to be given on the sixth anniversary of Sept. 11, FOX News has learned.

The warning was posted Sept. 2 on a site frequented by radical groups and said in part that "there will be a special gift coming on the day of the blessed invasion of Manhattan."

Federal officials told FOX News they are trying to determine if it might be a specific warning or just part of broad chatter that has been heard during the last few months.

Postings talking about "gifts" have been seen before in the days leading up to the anniversary of Sept. 11.

The Associated Press contributed to this report.