Houston: A Saudi Arabian student who is accused of purchasing chemicals and equipments to build explosive device and whose list of targets includes nuclear power plants and the residence of former president George W Bush, has submitted a plea of not guilty to a federal charge of attempted use of weapon of mass destruction.

Khalid Ali-M Aldawsari appeared at his arraignment on Monday morning in federal court in Lubbock, Texas, before US Magistrate Judge Nancy Koenig. Wearing a navy-blue prison jumpsuit, his hands and legs were shackled.

He faces a life sentence and a USD 250,000 fine if convicted.

Magistrate Koenig also put a trial date of May 2 for the convicted. A gag order exists in the case, so Aldawsari's defence attorney Rod Hobson, could not comment about yesterday's arraignment.

Hobson issued a written statement saying that his client should be "presumed innocent," earlier this year.

US District Judge Sam Cummings, the trial judge, early this month issued an order which prohibited Aldawsari's attorney or prosecutors from speaking about the case.

Court documents assert he hatched plans to attack various US targets, including in New York City and at former President Bush's Dallas home.

Hobson, the student's attorney, stood with his client and whispered to him after Koenig asked Aldawsari whether he wanted to waive the reading of his indictment.

"Waive," Aldawsari told Koenig. Aldawsari, who was legally in the US on a student visa, was convicted on February 23.

President Barack Obama had been notified about the plot, the White House said.

Court records indicate authorities traced Aldawsari's online purchases, discovered extremist online posts he made and secretly searched his apartment, computer and email accounts, and read his diary.

The terrorism case detailed in court documents was significant because it suggests that radicalized foreigners can live quietly in the US without raising suspicions from neighbours, classmates, teachers or others.

It also showed how quickly US law enforcement can move when tipped that a terrorist plot may be unfolding.

Federal authorities said a chemical company, Carolina Biological Supply of Burlington, NC, reported USD 435 in suspicious orders by Aldawsari to the FBI on February 1.

Separately, Ann Arbor, Mich.-based shipping company Con-way Freight notified Lubbock police and the FBI the same day with similar suspicions because it appeared the order
wasn't intended for commercial use.