A relative of Afghan President Hamid Karzai has been killed by international forces, Karzai’s brother and officials said Thursday.

The president’s brother, Ahmad Wali Karzai, told AFP that a relative, who he described as “our father’s cousin,” was shot dead near his home in the family’s village in southern Kandahar province by the US-led NATO force overnight.

“It was a mistake,” Ahmad Wali Karzai said. “The forces conducted an operation, he was at his home, he came out and was shot.”

The president was said to be “extremely sad” at the news, his spokesman said.

Ahmad Wali Karzai, a senior provincial politician who denies frequent accusations of involvement in the drugs trade, said: “It was a mistake. What can you do about it?”

The president learned of the incident Thursday morning, said his spokesman, Waheed Omer.

“He was extremely sad, just as he’s sad over any incident that takes the life of any innocent Afghan civilian,” Omer said.

Karzai “once again calls on NATO forces to avoid killing civilians,” the spokesman added.

An ISAF spokesman said the force was aware of the reports and was investigating.

The long-sensitive issue of civilian casualties caused by international troops has been high up the political agenda in Afghanistan recently.

Karzai rejected an apology from the US commander of foreign troops General David Petraeus over the deaths of nine children in an air strike last week.

A UN report out Wednesday revealed that the deaths of Afghan civilians in the war had increased 15 percent to a record high last year, adding that insurgents were responsible for three-quarters of the killings.

Meanwhile in Kandahar city, around 200 people marched on the provincial governor’s house bearing the dead bodies of three men who they said were innocent civilians killed by Afghan forces.

However, local officials say the three were gunmen and that the operation was targeting insurgents.