Paul Bremer says it will be impossible to organise elections in Iraq for another year to 15 months for technical reasons.
Al-Arabiya television broadcast excerpts from an interview with the US civilian administrator this morning.
Mr Bremer noted the absence in Iraq of voter lists or legislation covering elections and political parties as, he said, a visiting UN team highlighted last week.
Shi'ites, who contest US plans to hand power over to an unelected authority in the summer, have demanded to know when national polls will finally be held after UN Secretary General Kofi Annan recommended that elections be put off and a caretaker regime selected for the short term.
An Iraqi was killed and a US soldier wounded this morning when gunmen ambushed American civilian cars in Haswa, 30km southwest of Baghdad.
The attackers opened fire from a car, shooting dead an Iraqi translator and wounding a US soldier.
Two US soldiers and two Iraqis were killed yesterday by a roadside bomb near the city of Khalidiya, west of Baghdad.