An ethnic Somali US citizen has been detained without bail in Washington after his name and phone number appeared on a Washington road map found in a car registered to a man identified by the FBI as one of the hijackers who commandeered the American Airlines flight which crashed into the Pentagon.

Mohammed Abdi of Virginia was described by prosecutors as an essential witness who "may be more", Associated Press (AP) said on Wednesday. Abdi's lawyer insisted that the former airline food worker had no connection to the 11 September terrorist attacks in the US. Abdi was arrested on forgery charges unrelated to the attacks. The judge acknowledged that the charges against Abdi were ordinary, but said the connections to the attacks, even if tenuous, required him to err on the side of caution in denying bail.