A string of insurgent attacks has targeted civilians and government forces over the last three weeks, just a few months before limited withdrawals of US-led NATO forces are due to start in July.
Today's attack took place as people queued outside a district office in Imam Sahib in the northern province of Kunduz to collect new identity cards and other paperwork. Insurgents have made increasing inroads into the north, expanding from their traditional power bases in the south and east, along the Pakistan border, as they press a nine-year insurgency against the government and US-led troops.
District governor Mohammad Ayob Haqyar said a suicide attacker detonated his explosives in the waiting area.
"The number of people killed in the suicide blast rose to 31," he said. "Some of the critically wounded also died in hospital. Thirty-nine people are wounded." Officials locally and in Kabul said that all of the dead were thought to be civilians.
A local man, Mohammad Ismail, described the scene in the hospital where the wounded were being treated as chaotic.
"There are wounded and dead all over the floor in the hospital," he told AFP. "There are bodies with their chopped-off hands or legs next to them in the hospital. It's a disaster... you can hear screams everywhere."
Taliban spokesman Zabihullah Mujahid claimed one of its "hero" members had carried out the attack, which he said targeted an army recruitment centre and killed 30 members of the security forces.
The insurgent militia, which has been fighting the Western-backed government since being toppled from power in the 2001 US-led invasion, routinely deny killing civilians in their attacks.
Kunduz, in particular, has been volatile in recent months. Earlier this month, a suicide bomber killed a district governor and two others after walking into an office ostensibly to hand over a letter.
In the deadliest attack in Afghanistan since last June, four suicide bombers killed 38 people on Saturday, apparently targeting police collecting their salaries at a bank in the eastern town of Jalalabad.
On Friday, another nine people died in a car bombing near a district police headquarters in the eastern city of Khost. The previous week, 19 people including 15 police and an Afghan intelligence agent, died when suicide bombers armed with guns, grenades and car bombs targeted police in Afghanistan's de facto southern capital, Kandahar.