At least 12 Afghan civilians have been killed during a major military offensive in the south of the country, the Nato-led military force said.
The victims died after a rocket hit their house on Sunday, the second day of the offensive, which aims to wrest control of the town of Marjah and neighboring areas in Helmand province from the Taliban.
The statement said that the intended target of the rocket had been a Taliban compound from which fighters had shot and injured one Nato and one Afghan soldier.
The Nato-led force said that General Stanley McChrystal, the US and Nato commander in Afghanistan, had "apologized to Hamid Karzai, the Afghan president, over the deaths".
'Regrettable' deaths
The Isaf statement quoted McChrystal as saying: "The current operation in central Helmand is aimed at restoring security and stability to this vital area of Afghanistan.
"It's regrettable that in the course of our joint efforts, innocent lives were lost.
"We extend our heartfelt sympathies and will ensure we do all we can to avoid future incidents," he said.
Nato and US officials had earlier hailed the success, so far, of the offensive.
At least 27 fighters were reported to have been killed during the first day of fighting, while Nato said it had uncovered bomb-making materials and a weapons cache.
At least 15,000 US, British and Afghan soldiers have been involved in operations around Marjah.
PHOTO CAPTION
Map of Afghanistan locating the town of Marjah
Agencies