Afghan president Hamid Karzai has arrived back in Kabul after cancelling a planned trip to Britain following two bombings.
The attacks in the capital and northern city of Mazar-i-Sharif on Tuesday, 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 BBC reports 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.
Hamid 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 British Prime Minister David Cameron on Wednesday.
Mr Karzai said earlier it was "the first time that on such an important religious day in Afghanistan terrorism of that horrible nature is taking place".
He summoned his security chiefs for an emergency meeting early on Wednesday and would later visit a hospital in Kabul where dozens of people injured are being treated.
The BBC reports there are tensions between Sunni and minority Shia Muslims in Afghanistan, but violence of the type seen in Pakistan or Iraq is rare.
The Taliban, the main militant group responsible for most attacks in Afghanistan, have denied responsibility for the bombings. Police said they foiled another attack elsewhere in the capital.