Accused Tucson, Ariz., shooter Jared Loughner pleaded not guilty on Monday to charges of trying to kill a member of Congress and attempting to kill two federal employees.

The man accused in the Tucson, Ariz., shootings that killed six and wounded U.S. Representative Gabrielle Giffords and a dozen other people pleaded not guilty on Monday.

Jared Loughner, 22, entered the plea to charges of trying to kill a member of Congress and attempting to kill two federal employees — a pair of Giffords's aides who were among the wounded.

U.S. District Judge Larry Burns asked Judy Clarke, Loughner's attorney, whether there was any question about the accused man's ability to understand the case against him.

"We are not raising any issues at this time," Clarke said.

Loughner appeared in court smiling and wearing an orange prison suit and glasses. His hair, which was shaved off in earlier photos, was beginning to grow back. He is currently being held without bail as he awaits trial.  

Loughner did not speak during his court appearance on Monday.

He could still face additional federal charges for the killing of Arizona Democrat Giffords's aide and U.S. District Judge John Roll. Loughner also expected to face state charges in connection with the other victims.    

Prosecutor Wallace Kleindienst said he expected to know within the next 30 days whether additional federal charges will be filed against Loughner.

Burns on Monday did not rule on a request made a day earlier by the U.S. attorney for Arizona that the federal case be transferred back to Tucson for all further hearings.

The motion argued that the victims and witnesses live in the Tucson area and should not be burdened by having to make a four-hour round-trip drive to Phoenix to attend court hearings.

Local Federal Court rules also require that a crime that happens in the court's Tucson region should be tried there unless a court moves the case.

The case was moved to Phoenix because Roll was based in Tucson, where federal judges recused themselves. All the federal judges in the rest of the state soon joined them, and a San Diego-based judge is now assigned to the case.

Meanwhile, the Houston hospital treating Giffords said in a statement Sunday that her condition is "improving daily" but gave no update on the buildup of brain fluid that has kept her in intensive care.

The statement said the Arizona congresswoman would continue to receive therapy "until her physicians determine she is ready for transfer" to a nearby centre where she would begin a full rehabilitation program.

Giffords was flown to Memorial Hermann Texas Medical Center Hospital on Friday from Tucson. Shortly after her arrival, doctors said she had been given a tube to drain excess brain fluid, which can cause pressure and swelling.

With files from The Associated Press