Media playback is unsupported on your device Media caption Crowds of well-wishers turned out to wave at the ambulance carrying Ms Giffords

Doctors treating US Congresswoman Gabrielle Giffords said her transfer from a hospital to a rehabilitation centre had gone "flawlessly".

At Memorial Hermann Rehabilitation Hospital in Texas, Dr Randall Friese said she had smiled and shed tears on hearing applause from well-wishers.

The Arizona Democrat was shot in the head at a shooting at a constituency meeting in which six people died.

Jared Loughner, 22, has been jailed pending trial for the attack in Tucson.

Ms Giffords was flown from Tucson, the largest city in her Arizona constituency, to William Hobby Airport in Houston on Friday afternoon, from where she was transported to the rehab facility.

At a news conference later at Memorial Hermann, where she will undergo extensive rehabilitation, doctors described her condition as "spectacular", with "great" potential for recovery.

The doctors said she had moved limbs on her left side and showed good muscle tone, that she was aware of her surroundings and was interacting non-verbally with doctors and family members.

Part of Ms Giffords' skull has been removed to accommodate swelling on her brain, and doctors said they had fitted her with a helmet bearing the Arizona state flag, at the request of her husband.

During the drive from the Tucson hospital to the air base from which she flew to Texas, Ms Giffords appeared to smile and shed tears on hearing applause from well-wishers by the side of the road, doctors said.

But despite her steady progress, doctors say Ms Giffords still has a long road to recovery and are not sure what disability, if any, she will have.

'Biggest smile'

On Thursday, hospital workers in Tucson brought Ms Giffords to an outside deck where she was given the opportunity to breathe fresh air and feel the sun, trauma surgeon Peter Rhee said.

Image caption Mrs Giffords is being transported to a rehabilitation clinic in Houston in the state of Texas

"I saw the biggest smile she could gather," Mr Rhee said, adding that those at the hospital are "very happy to have her enjoying the sunshine of Arizona."

A University Medical Center spokeswoman said Ms Giffords had also been able to scroll through an iPad, and had picked out colours and moved her lips.

Hospital staff are also unsure of how well the congresswoman can see.

Earlier this week, Ms Giffords reportedly stood, aided by medical staff.

Mr Kelly said on Thursday he believed she was attempting to speak and could recognize those around her, calling his wife "a fighter like nobody else that I know".

"I can just look in her eyes and tell," Mr Kelly said, adding that he is hoping she will make a full recovery.

Ms Giffords' mother has said the Democratic congresswoman has made remarkable progress since the early January attack at a constituency event outside a store in Tucson.

Mr Loughner was indicted earlier this week on three counts of attempting to kill federal officials, relating to Ms Giffords and two of her aides wounded in the assault.

The indictment does not include a charge in the death of John Roll, a federal judge. The Arizona US attorney described the initial indictment as the beginning of federal legal action against Mr Loughner.

State charges are also likely to follow.