London- Taliban attack on an army-run school in the Pakistani city of Peshawar shows a merciless disregard for human life and highlights the urgent need for protection of civilians in the area, a leading rights group has said.

At least 141 people, mostly children, were killed when Taliban suicide attackers stormed the school and began firing indiscriminately at students and teachers yesterday, in one of the most shocking Taliban attacks in recent memory.

"There can be absolutely no justification for targeting children in this way. This unconscionable Taliban attack is a grave reminder that civilians in north-west Pakistan desperately need effective protection from militant groups," said David Griffiths, Amnesty International's Deputy Director for Asia-Pacific.

"Of prime importance now is that the Pakistani authorities take effective steps to protect civilians and minimize the risk of this type of sickening tragedy being repeated," Griffiths said.

The Taliban have targeted students in Pakistan on numerous occasions, but this is by far their deadliest attack on a school. Since 2010, there have been at least four attacks on school buses including the one in which Nobel Peace Prize winner Malala Yousufzai, was shot in the head in Swat in 2012. There have been at least three Taliban attacks on schools this year, with one fatality, Amnesty added.