Amnesty International has accused the so-called international community of failing to protect civilians in Afghanistan.
Amnesty secretary general Irene Khan said: "The rapid advance of the Northern Alliance into Kabul without any international arrangements to safeguard civilians is a clear indication that the military agenda has overtaken human rights concerns."
Ms Khan said the Afghan population is at the mercy of Northern Alliance, a loose collection of armed political groups with appalling human rights records.
Amnesty has also expressed concern about summary executions of Taliban soldiers amid reports that 100 child recruits were butchered by the Northern Alliance when it overran Mazar-e-Sharif on Friday night.
There are also unconfirmed reports that the Alliance has lynched several Taliban soldiers in the streets of Kabul.
Ms Khan said: "Human rights abuses committed by the Taliban cannot be used to justify new abuses by the Northern Alliance. These killings must stop."
Referring to the US, Britain and Russia, she added: "Those countries which supplied arms to and supported the Northern Alliance are responsible for ensuring that the Alliance conducts itself within international humanitarian law and does not use its arms to commit further abuses.
"If there is bloodshed, the blood is also on their hands. They must fulfil their responsibility and ensure that civilians are protected and ensure that the political future of Afghanistan is a fair and inclusive one, based on respect for human rights without discrimination."