A suicide bomber detonated explosives inside both Shiite and Sunni mosques on Friday in Kabul as worshippers gathered for evening prayers.
An Afghan official at the Interior Ministry says the attack that took place in the western Dasht-e-Barchi part of the Afghan capital killed at least 56 people and wounded 55.
Major General Alimast Momand said the attacker was on foot and walked into to the Imam Zaman Mosque where he blew himself up.
A security source told the dpa news agency the death toll could rise to between 70 and 80.
The "Islamic State" claimed credit for the attack, but did not provide evidence. The group often claims attacks that it did not carry out.
Early on Saturday, at least two rockets landed near the international military headquarters in the city's downtown area. Alarms went off at the NATO-led military mission and several foreign embassies nearby. No casualities were reported.
Afghanistan's Shiite minority has witnessed several attacks this year. At least 84 people have been killed and 194 wounded in attacks on their mosques and religious ceremonies, a United Nations report released last week said.
Among them were two attacks on Shiite mosques in Kabul in August and September.
Separate bombing at Sunni mosque
In Ghor, another suicide bomber blew himself up inside Khewiagan, a Sunni mosque in the district of Dulaina, killing at least 33 people.
Iqbal Nizami, a spokesman for the Ghor provincial police, told Reuters news agency the bombing appeared to target a local leader.
The targeted official, a top local political and military leader of the Jamiat political party in Ghor, was killed along with other worshippers, according to a statement from Balkh provincial governor Atta Mohammad Noor.
No organization has claimed responsibility for either attack.
Afghanistan President Ashraf Ghani condemned the attacks. He said the country's security forces would step up the fight to "eliminate the terrorists who target Afghans of all religions and tribes."
ap,mm/ng (Reuters, dpa, AP)