KABUL, Afghanistan -- Within hours of the top United Nations official in Afghanistan issuing a statement saying the Taliban had "signaled their willingness" to talk about reducing civilian casualties, militants set off a bomb that killed at least 17 civilians and wounded 39 others, many of them critically, outside the capital's Supreme Court complex on Tuesday.
The powerful explosion, felt throughout central Kabul, destroyed three buses taking court workers home from their jobs, said Gen. Dawood Amin, the deputy police chief in Kabul. He said the death toll might rise as the authorities searched for bodies. The victims included at least nine women and several children, he said, but no police or military personnel.
The Taliban spokesman, Zabiullah Mujahid, e-mailed a statement to reporters afterward saying that a suicide bomber had carried out the attack, and that the court's employees had been "sentenced to death" because of their "important role in cruelty, bad behavior with our countrymen, and legalizing the infidels."
Most of the victims, however, were believed to be low-level employees.
Earlier in the day, Jan Kubis, the United Nations secretary general's special representative, said at a news conference that the Taliban had made "rather recent" responses to overtures from the United Nations seeking to discuss civilian casualties. "I can confirm that we received signals about their willingness and readiness to discuss this issue with us," he said. "I welcome this."
Mr. Kubis also deplored what he said was a 24 percent increase in civilian casualties this year through June 6 compared with the same period in 2012, and he blamed the insurgents for three-quarters of those, based on data compiled by the United Nations.
That provoked an angry reaction from Mr. Mujahid, who said in a telephone call that the United Nations "should not act as a propaganda machine for the invaders in Afghanistan."
He said he "would not confirm" that the Taliban were considering any such talks. However, he maintained that "our mujahedeen have been strictly advised to exercise maximum caution when conducting an operation in an area populated by civilians."
There was little evidence of such caution on Tuesday afternoon, however. The suicide bomber drove his car into the employee buses when the largest number of court workers would be present, about 20 minutes after work let out at 4 p.m. but before the buses were fully loaded.
Witnesses and policemen described a scene of devastation, with three buses destroyed and body parts strewn over an area as wide as 200 yards from the blast's center.
Most of the victims appeared to be Supreme Court workers, said Mujib Aziz, the secretary to the chief justice, who was reached by telephone in the court's bunker. The chief justice himself was in his office during the attack and was unharmed, Mr. Aziz said.
The attack came a day after an unsuccessful assault on the Kabul airport, in which no one was killed.
Mr. Kubis said earlier on Tuesday that the United Nations had publicly and through private channels asked the Taliban to engage in the talks on civilian casualties. "Now we are discussing modalities, how hopefully to start this dialogue, sooner rather than later," he said. "We need to come to an understanding how to do this; as you know it's not that simple to have a meeting between the two of us."
Such talks would be limited to the issue of civilian casualties, rather than broader peace initiatives. There have been secret peace talks between the United Nations and the Taliban in previous years, but no known ones recently.
Mr. Kubis did not give a detailed breakdown of civilian casualty figures, which will be covered in a report due out next month. But he expressed concern that the latest data show a marked increase in civilian casualties over last year, when there was actually a decrease.
Mr. Kubis said 21 percent of the 3,092 civilian casualties this year had been children, a rise of 30 percent over the previous year.
"This is unacceptable," he said.
He did not provide a breakdown of how many of the victims were killed and how many wounded. Mr. Kubis also said that civilian casualties caused by improvised bombs increased 41 percent compared with last year, and that targeted killings or assassinations by insurgents rose 42 percent. Deaths from airstrikes carried out by the coalition continued to decline, by 30 percent so far this year.
The rise in casualties over last year may well reflect the weather more than the tempo of the war. This winter was mild and short, while last year it was severe and long, helping curtail some of the violence.
Sangar Rahimi, Sharifullah Sahak and Habib Zahori contributed reporting.
This article originally appeared in The New York Times.