Riyadh, Saudi Arabia ? Despite official denials, there have been signs for months that Saudi Muslim extremists have traveled to Iraq to take on U.S.-led forces.

Internet memorials to those who died fighting the Americans have popped up, and Saudis are quietly swapping tales said to be from the front lines. Many of the men going to Iraq had previously fought in Afghanistan, Chechnya and Bosnia and were experts on guerrilla warfare, said Abdullah Bjad al-Otaibi, who once counted himself among the extremists and now writes about them for Saudi newspapers.

Saudi extremists are “looking to die and the quickest way to heaven, as far as they’re concerned, is fighting infidels, in this case represented by the U.S. forces in Iraq,” al-Otaibi said. “Nothing inflames their emotions like the presence of U.S. troops in a Muslim country. The presence of the troops in Iraq, especially with the instability there, is like a magnet to them.”

Saudi officials, sensitive to any charges extremism may be emanating from the kingdom, have categorically dismissed the possibility their citizens are fighting in Iraq. In an interview with the London-based Arabic newspaper Al-Hayat published Saturday, Saudi Interior Minister Prince Nayef called such allegations “baseless.”

In Washington last week, Saudi foreign policy adviser Adel al-Jubeir challenged the Bush administration to prove suggestions from U.S. Deputy Secretary of State Richard Armitage and others that some of those attacking U.S. troops in postwar Iraq were from Saudi Arabia.

“We have no evidence of Saudis crossing into Iraq and we have received no evidence from the U.S. government,” al-Jubeir told The Associated Press