The shooting of 14-year-old Malala Yousafzai on a school bus in the Swat valley has been denounced worldwide and by the Pakistani authorities, who have offered a reward of more than $100,000 for the capture of her attackers.

Two of her school friends were also injured in the attack, carried out as retribution for Malala's campaign for the right to an education during a two-year Taliban insurgency.

"Now she needs post surgery care. The doctors recommended that AFIC (Armed Forces Institute of Cardiology) has better facilities for post-surgery care," military spokesman Major General Asim Saleem Bajwa told AFP.

Another official later confirmed she had arrived by helicopter in Rawalpindi, the twin city of the capital Islamabad and the headquarters of the Pakistan army.

Bajwa said Malala was still unconscious and that the next 24 hours would be crucial.

On Wednesday, she underwent an operation to remove the bullet from between her shoulders in a military hospital in Peshawar.

"She has been put on a ventilator for two days. The bullet has affected some part of the brain, but there is a 70 percent chance that she will survive," one of her doctors, Mumtaz Khan, told AFP.

Mehmoodul Hasan, one of Malala's relatives, said the family had been told doctors were sending her medical reports abroad for advice.

"They are checking if better facilities are available in the UK or Dubai or any other country, then they will decide about sending her abroad, otherwise they will treat her here," said Hasan.

US President Barack Obama, UN chief Ban Ki-moon and Pakistani leaders have expressed horror at the attack on a girl who won admiration for daring to speak out during the Taliban insurgency, which the army said it had crushed in 2009.

Obama believed the shooting was "reprehensible and disgusting and tragic", said White House spokesman Jay Carney.

Officers in Swat say dozens of people were rounded up after the attack but no one has been charged.

Mingora police station chief Ahmad Shah told AFP that nearly 200 people had been detained over Malala's shooting, including the bus driver and a school watchman, but that most had been released.

Commentators believe little will change after the shooting, despite a call from the army chief General Ashfaq Kayani to further unite against militants and their "barbaric mindset".

Many in the country blame the United States and the war in neighbouring Afghanistan for the violence. The military has been accused of playing a double game in supporting or at least accommodating Islamist militant groups.