The official told Reuters on Wednesday: "Jaber Elbaneh was a member of the cell and was among those who escaped from prison in Yemen."
In May 2003, US prosecutors charged Elbaneh with conspiring with six other Yemeni-American men who admitted they were trained in April 2001 at a camp in Afghanistan run by Osama bin Laden's al-Qaida network.
The cell was dubbed "Lackawanna 6" after their home town in New York.
Elbaneh, 39, was charged with providing material support to a terrorist organisation and conspiring to provide such support specifically to al-Qaida.
The seven men were never accused of violence or involvement in the September 11 attacks, but the US government said they engaged in a conspiracy of silence before and after the 2001 attacks that killed nearly 3000 people.
"There were seven US citizens of Yemeni origin who grew up in Lackawanna, New York, and Elbaneh was one of them. All seven of them reportedly travelled to an al-Qaida training camp in Afghanistan in the summer of 2001," the official said.
"Elbaneh never returned to the US after his training in Afghanistan. The other six of the Lackawanna cell were arrested when they returned to the US."
Elbaneh was arrested in late 2003 in his native Yemen, which is bin Laden's ancestral homeland.
His current whereabouts are unknown, but Yemen has launched an intensive manhunt for the group of 23 prisoners, including at least 13 convicted al-Qaida members, who tunnelled their way out of a jail in the capital Sanaa.
Interpol issued a global security alert on Sunday, calling the escaped militants a "danger to all countries".
The jailbreak was a major embarrassment for Yemen, which has cracked down on militants and has sought to position itself as an ally of the United States.
Jamal al-Badawi plotted the
bombing of the US destroyer Cole
The escapees included Jamal al-Badawi, mastermind of the bombing of the US destroyer Cole in the Yemeni port of Aden in October 2000, which killed 17 US sailors.
Another is Fawaz al-Rabe'ie, who led the group convicted of bombing the French oil tanker Limburg off the Yemeni coast in 2002, killing a crewman.
According to the US government's Rewards For Justice Web site, which details the rewards for helping track down wanted militants, Elbaneh is about 1.73m tall, weighs 90kg and has brown hair and eyes. He is pictured with a moustache and beard.