A bomb blast inside a mosque in eastern Afghanistan that was being used as a voter registration center killed at least 14 people and wounded 33, officials said.

Habib Shah Ansari, the provincial head of public health, confirmed the toll from the attack, which took place in the city of Khost, the capital of the province of the same name.

The bomb had been placed in a tent being used to register voters on the grounds of a mosque, Khost provincial police chief Abdul Hanan Zadran told AFP.

"A crowd of people who had come out of the mosque had gathered to register" when the blast took place, he added.

"Some wounded people are in critical condition and ambulances are still bring more people," provincial deputy director of public health Gul Mohammad Mangal told AFP.

No one immediately claimed responsibility for the attack, but both the Taliban and a local Daesh terror group affiliate reject democratic elections and have targeted them in the past. Daesh is not known to have a presence in Khost, but has expanded its footprint into other areas in recent years.

It was the latest attack on election preparations and comes almost a week after 25 people were killed in two attacks in the Afghan capital Kabul.

Nine journalists including AFP chief photographer Shah Marai were among the dead. BBC reporter Ahmad Shah was killed in a separate attack in Khost province.

Last month, a Daesh suicide bomber attacked a voter registration center in Kabul, killing 60 people and wounding at least 130 others.

Afghanistan plans to hold elections in October, the first since 2014.

The Taliban and Daesh have launched a relentless wave of attacks since the start of the year, killing scores of civilians in the capital, Kabul, and elsewhere. Afghan security forces have struggled to combat the groups since the U.S. and NATO concluded their combat mission at the end of 2014, switching to a counter-terrorism and support role.

Elsewhere in Afghanistan, a vehicle carrying shopkeepers on their way to a market struck a roadside bomb in Afghanistan's northern Faryab province, killing seven of them. Police spokesman Karim Yuresh said another civilian was wounded in Sunday's attack, in an area where both the Taliban and Daesh are active.

In the eastern Paktia province, a car bomb killed two people and wounded another three. Abdullah Hsart, the provincial governor's spokesman, said the attack late Saturday targeted Hazart Mohammad Rodwal, a district chief, who was among the wounded. The Taliban claimed the attack.