Afghan President Karzai cancels UK trip after bombings
Afghan President Hamid Karzai has cancelled a visit to the UK to return to Afghanistan, after Tuesday's deadly attacks in the capital, Kabul, and in the northern city of Mazar-i-Sharif.
The twin attacks apparently targeting Shia Muslims killed at least 58 people.
A suicide bomb struck a Kabul shrine, killing at least 54, while the other blast struck near a Shia mosque in Mazar-i-Sharif at about the same time.
The attacks seemed to be sectarian, raising fears of new violence.
Mr Karzai was in Germany on Tuesday evening after attending the international conference on his country in Bonn, and was later due to travel to the UK for talks with UK Prime Minister David Cameron on Wednesday.
He said earlier it was "the first time that on such an important religious day in Afghanistan terrorism of that horrible nature is taking place".
The blasts coincided with the Shia Muslim festival of Ashura - the most important day in the Shia calendar which is 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.
Though tensions exist between Afghanistan's Sunni and minority Shia Muslims, most attacks in Afghanistan in recent years have targeted government officials or international forces, correspondents say.
Violence of the type seen in Pakistan or Iraq is rare, the BBC's Quentin Sommerville in Kabul says.
Pakistan boycotted the Bonn conference after a Nato attack killed 24 of its troops at a checkpoint near the Afghan border last month.
Afghan security officials held their breath during the conference, our correspondent says, fearing there might an attack in Kabul to divert attention.
The near-simultaneous explosions happened at about midday (07:30 GMT).
In Kabul, the bomb went off near a gathering of hundreds of Shias singing at the Abu Fazal shrine, killing 54 people and injuring 150.
No-one had claimed to have carried out the attacks, said Mohammad Zahir, head of Kabul's criminal investigation department.
A Taliban statement said the group had not been behind either incident.
Mohammad Bakir Shaikzada, the top Shia cleric in Kabul, said he could not remember a similar attack on such a scale.
Police said they foiled another attack elsewhere in the capital.
The bomb which exploded near the main mosque in Mazar-i-Sharif was apparently strapped to a bicycle, and went off shortly after the Kabul blast.
Four people were killed and 17 injured in that attack.