Dozens more were hurt in the blast, some critically. Most of the casualties were civilians.

Militants often target Afghan state employees as well as foreign forces.

Officials blamed the Taliban, but a Taliban spokesman said it did not attack public places, adding the blast was caused by "someone with an agenda".

Provincial official Din Mohammad Darwaish said the death toll could well increase as there were still people buried under rubble.

A large number of people had gathered at the clinic in Azra district, for weekly treatment, many of them women and children, he said.

The attack comes a day after 10 people were killed and 24 injured in a blast in northern Kunduz province.

On June 22, US President Barack Obama announced a partial troop pull-out from Afghanistan.