The picture, which appeared on a U.S. Web site, showed the presidential hopeful in a white headdress and traditional Somali attire during a 2006 visit to Wajir in Kenya's remote northeast.

The Illinois senator has battled a whispering campaign by fringe elements who wrongly say he is Muslim, and aides accused his Democratic party rival Hillary Clinton's camp of "the most shameful, offensive fear-mongering" after it was published.

Incensed at the implication that Obama, whose late father was from western Kenya, did anything wrong on his visit, elders in Wajir have demanded an apology and vowed to demonstrate.

"The clan he was with have every right to be offended," said Hussein Ali, a 32-year-old unemployed man outside the main Jamia Mosque in the capital Nairobi.

"Obama's enemies are trying to portray him as a terrorist, saying all Muslims, and especially Somalis, are dangerous men."

Many in the east African country support Obama the way the Irish idolised U.S. President John F. Kennedy in the 1960s -- as one of their own who succeeded beyond their wildest dreams.

Clinton's campaign denies authorising the release of the controversial photo, but says that with 700 staffers it could not be known whether someone had sent it out unofficially.

That has not mollified elders in Wajir, a small desert town near the Somali border, who demanded she "clear her name". Other Kenyans questioned the timing of the picture's publication, just days before make-or-break votes in Ohio and Texas next week.

For many Americans, Somalia conjures up disturbing images of dead U.S. troops being dragged through Mogadishu's dusty streets during the "Black Hawk Down" battle of 1993.

The U.S. military launched air strikes on the Horn of Africa country last year in its hunt for al Qaeda, including suspects wanted over the bombing of the U.S. Embassy in Nairobi in 1988.

"We suspect the intent behind releasing this picture now, just before Tuesday's very critical vote," said Omar Jamal, head of the St Paul, Minnesota-based Somali Justice Advocacy Centre.

His lobby group, which works with Somali immigrants in the United States, has also demanded an apology from Clinton's camp.

"They are trying to make a link between a man who could be the next U.S. president and a country with al Qaeda terrorist activities. They're trying to tell citizens, look who you might be voting for," he told Reuters by telephone.

"Everyone is very upset. It's outrageous and undermining."

Once the odds-on favourite to win the party's nomination to run against a Republican candidate in the November election, Clinton has lost big opinion poll leads in Texas and Ohio as Obama has gained momentum and made inroads among her supporters.