Al-Qaida has identified a would-be 20th hijacker for the Sept. 11 attacks as a Saudi operative who was killed in a 2004 shootout with his country's security forces.

In a statement accompanying a new video, the terrorist network's propaganda arm identified Fawaz al-Nashimi, also known as Turki bin Fuheid al-Muteiry, as the operative who would have rounded out a team that ultimately took over United Airlines Flight 93, which crashed into a Pennsylvania field before reaching its intended target.

A 54-minute video featuring al-Nashimi was obtained Tuesday by IntelCenter, a US government contractor based in Virginia. US counterterrorism officials declined to comment on the authenticity of the video and its claims.

The video included a screen crediting the al-Sahab media committee with producing the message. While no one is known to have forged the group's work, its statements are often difficult to verify.

The video includes footage of al-Nashimi justifying attacks against the West. It also contains 27 minutes of previously unheard audio of a siege that he took part in on oil facilities in Khobar, Saudi Arabia.

Screeching car tires and gunfire are heard as the terror cell moved from building to building. A voice in Arabic can be heard saying: "Where are the Americans? ... Give me the information."

The demands are punctuated with more gunfire.

In the May 2004 attack, militants dressed in military-style uniforms opened fire inside two oil industry office compounds, then moved to an upscale residential area. They took 45 to 60 hostages.

Saudi security forces stormed the complex, but three of the militants escaped, including al-Nashimi. Twenty-two people were killed in the 25-hour rampage, almost all of them foreigners, including one American.

Al-Nashimi was killed the following month in gunbattle with Saudi forces.

The Khobar assault was one of a series of attacks against foreigners by al-Qaida's Saudi branch in 2003 and 2004, aimed at undermining its US-allied royal family.

If the statements on the new video are true, they would also fill in a missing piece of the puzzle of the attacks on Sept. 11, 2001.

US counterterrorism officials have believed for some time that the original 9/11 plot included another hijacker on United Airlines Flight 93, which only had four attackers. The two planes that flew into the World Trade Center towers and the one that flew into the Pentagon each had five hijackers.

Federal agents at first thought Zacarias Moussaoui was intended to be on Flight 93, but later revised their allegations. Moussaoui further muddied the waters during his terrorism trial, when he claimed - and later recanted - that he was supposed to fly a fifth plane on Sept. 11 into the White House.

During a May audio message, Osama bin Laden said Moussaoui was not the 20th hijacker "as your government has claimed." He didn't provide the actual identity. Moussaoui pleaded guilty to conspiring with al-Qaida to fly planes into US buildings and is serving a life sentence at a federal prison in Colorado.

The Sept. 11 commission identified yet a third person as a possible 20th hijacker: al-Qaida member Mohammed al-Kahtani, who was turned away at Orlando International Airport in Florida in August 2001.