Twin attacks apparently targeting Shia Muslims have killed at least 58 people in Afghanistan.

In the deadliest incident, a suicide bomb struck a shrine packed with worshippers in the capital, Kabul, killing at least 54 people.

Another blast struck near a Shia mosque the northern city of Mazar-i-Sharif at about the same time, killing four.

The attacks appear to be of a sectarian nature unprecedented in recent Afghan history, correspondents say.

They coincided with the Shia Muslim festival of Ashura - the most important day in the Shia calendar and marked with a public holiday in Afghanistan.

Ashura is the climax of Muharram, the month of mourning for the martyrdom of the Prophet Muhammad's grandson.