UN said the toll includes 14 children as concern over air raids killing more civilians grows in the country.
At least 23 civilians, including women and children, were killed by an air raid carried out by the United States in southern Afghanistan earlier this week, according to a UN investigation.
“Initial findings indicate that the vast majority of the victims were women and children,” the UN mission in Afghanistan said in a report received by AFP late on Thursday, adding that at least three people were also injured in the attack.
The attack occurred during a firefight between Afghan special forces working with US advisers and Taliban fighters late on Tuesday in restive Helmand province.
NATO said air support was requested by security forces on the ground as the fighters deployed heavy weapons and retreated into a nearby compound.
Provincial authorities had earlier said several members of a single family appeared to have been killed in the attack, with one official saying “at least 18 civilians were killed”, which could not be confirmed.
NATO has said it was investigating the incident.
Haji Mohammad, who lived near where the incident occurred, said the attack came after the Taliban entered a home during a battle with security forces, saying it killed several civilians inside along with nine fighters.
Civilians continue to face “extreme levels of harm”, a recent UN report said, with 8,050 people killed or wounded in the January to September period this year.
Violence has escalated in the past year as US and Afghan forces press ground and air offensives against the Taliban and the armed group the Islamic State of Iraq and the Levant (ISIL, also known as ISIS).
The Taliban has also upped assaults on Afghan forces even as the US increased efforts to engage the fighters in peace talks.
Washington is trying to find a way out of the conflict more than 17 years since the US intervention that toppled the Taliban from power.
US envoy Zalmay Khalilzad is spearheading efforts to strike a peace deal with the Taliban before Afghanistan’s presidential election, scheduled for April next year, though officials have said it could be postponed until July.
A Taliban delegation met Khalilzad in Doha, the Qatari capital, in October and November to discuss ending the Afghan conflict.
Khalilzad has said he is “cautiously optimistic” for an end to the conflict.
Meanwhile, President Ashraf Ghani announced in the Swiss city of Geneva on Wednesday that his government has appointed a 12-member team to hold talks with the Taliban.
Also on Friday, at least 29 people were killed in clashes between a pro-government militia commander and the Taliban in Herat province, according to provincial governor spokesman Jelani Farhad.