The judge, citing delays, said Tuesday he wanted to "get this case on track," The New York Times reported. Among other things, Mansour J. Arbabsiar of Corpus Christi, Texas, is accused of conspiring to hire assassins from a Mexican drug cartel to kill the ambassador for $1.5 million.
The defendant has been in custody since he was arrested Sept. 29 at Kennedy International Airport in New York.
The matter has strained already tenuous U.S.-Iran relations and is expected to result in a legal challenge over the statements Arbabsiar reportedly voluntarily gave to authorities during 12 days of interrogation, observers said. Arbabsiar didn't go before a judge nor was he given a lawyer until Oct. 11, when his case was announced, the report said.
Prosecutors have said Arbabsiar repeatedly waived his rights to remain silent, have a lawyer present during questioning and be taken before a judge quickly after his arrest.
Prosecutors also said Arbabsiar "confessed to his own role in the plot" and "provided extremely valuable intelligence," the Times reported.
On Tuesday, presiding Judge John F. Keenan pressed the prosecution to speed up its delivery of discovery material to the defense and expressed dismay at a defense request for a later trial date, the Times said.
"The man is in prison. He's awaiting trial. It's an important case," Keenan said. "I don't want this thing dragging on. It's not fair to the defendant; it's not fair to the government or to the witnesses in the case."
Arbabsiar, 56, has pleaded not guilty. He is one of two Iranian men implicated in the alleged plot to assassinate Abel al-Jubeir, the Saudi ambassador to the United States. The other suspect, Gholam Shakuri, remained at large.
U.S. officials, aided by an undercover informant, arrested Arbabsiar on suspicion that he conspired with Shakuri, allegedly a member of Iran's Revolutionary Guards, to hire the assassins to detonate a bomb at a restaurant where Jubeir was going.
The Iranian Foreign Ministry has said the accusations are groundless. Iranian media have said Shakuri is an operative of an exiled Iranian opposition group.