An injured student is transported to a hospital after a bomb explosion near a school in west of Kabul, Afghanistan, on Saturday. AP

The death toll from bombs planted outside a girls' school in an area of the Afghan capital populated largely by Shiite Hazaras rose to 50 Sunday as the Taliban denied government accusations that they were behind the bloody attack.

The Saturday's blasts — the deadliest in more than a year — rocked the west Kabul district of Dasht-e-Barchi, a regular target of militants.

It comes as the United States military continues to pull out its last 2,500 troops from the violence-wracked country despite faltering peace efforts between the Taliban and Afghan government to end a decades-long war.

Arian's deputy Hamid Roshan told AFP that an investigation had begun into the explosion, adding that casualties included students.

"I saw many bloodied bodies in dust and smoke, while some of the wounded were screaming in pain," Reza, who escaped the blast, told AFP, adding that most of the victims were teenaged female students who had just left the school.

Health ministry spokesman Dastagir Nazari said several ambulances had been rushed to the site and were evacuating the wounded. He said an angry crowd had beaten the ambulance workers at the site.

No organisation took responsibility for the attack and the Taliban denied involvement. But President Ashraf Ghan blamed the group for the blast, which took place near the entry gate of Sayed Al Shuhada girls' school.

Relatives try to identify the bodies at a hospital after a bomb explosion near a school in Kabul. AP

This savage group (Taliban) does not have the power to confront security forces on the battlefield, and instead targets with brutality and barbarism public facilities and the girls' school," he said in a statement.

'Despicable act of terrorism'

The Taliban has denied carrying out attacks in Kabul since February last year, when they signed a deal with the United States that paved the way for peace talks and withdrawal of the remaining US troops. But the group has clashed in near-daily battles in the rugged countryside with Afghan forces even as the US military continues its withdrawal.

An injured school student is transported to a hospital after a bomb explosion near a school. AP

The European Union delegation in Afghanistan condemned what it said was a "despicable act of terrorism." "Targeting primarily students in a girls' school, makes this an attack on the future of Afghanistan. On young people determined to improve their country," it said on Twitter.

The United Nations Assistance Mission in Afghanistan (UNAMA) expressed its "deep revulsion" at the blast. The Dasht-e-Barchi neighbourhood has been a regular target of attacks from militants.

Agence France-Presse