Tens of thousands have rallied in Pakistan in support of a 14-year-old girl shot and critically wounded by the Taliban for promoting girls' education and criticising the militant group.

The demonstration in the southern city of Karachi was the largest by far since Malala Yousufzai and two classmates were shot October 9 while returning home from school.

The rally was organised by the most powerful political party in Karachi, the Muttahida Quami Movement. The party's chief, Altaf Hussain, addressed the audience by telephone from London, where is he in exile.

Mr Hussain called the Taliban gunmen "beasts" and said the shooting was an attack on "the ideology of Pakistan".

The demonstrators carried the young girl's picture and banners praising her bravery.

It came as Afghan President Hamid Karzai wrote to top political and religious leaders in Pakistan, denouncing the attack.

He said the attack on Malala indicated that both Afghanistan and Pakistan need to take co- ordinated steps to fight terrorism and extremism.