KABUL — The NATO-led foreign military force in Afghanistan admitted Thursday that a US soldier shot dead an Afghan journalist working for the BBC in July after mistaking him for a suicide bomber.

Ahmed Omed Khpulwak, 25, was killed in a case of "mistaken identity" shortly after a suicide bombing on the office where he was working in troubled southern Afghanistan left 20 people dead.

The US soldier responsible for his death is not facing any disciplinary action in connection with the incident, International Security Assistance Force (ISAF) spokesman Lieutenant Colonel Jimmie Cummings said.

Cummings could not confirm whether the soldier was still on active duty in Afghanistan.

"After a thorough investigation, it was determined the reporter was killed in a case of mistaken identity," ISAF said in a statement.

"Mr Khpulwak was shot by an ISAF member who believed he was an insurgent that posed a threat and was about to detonate a suicide vest improvised explosive device."

It said the soldier involved had "complied with the laws of armed conflict and rules of engagement and acted reasonably under the circumstances."

Khpulwak's death on July 28 came after two suicide bombers struck at the offices of state broadcaster RTA (Radio Television Afghanistan) in Uruzgan province in Afghanistan's south, an area regarded as the Taliban's heartland.

US forces were sent to the scene to fight the insurgents.

They were clearing the building after the suicide bombers had blown themselves up when a soldier saw Khpulwak near a broken wall and others believed they heard him fire a shot.

Another soldier approached him and saw him "with something clinched in one of his fists and reaching for something on his person with his other hand," ISAF's summary of a report into the incident said.

"The soldier assessed the actions as those of a suicide bomber who was taking steps to detonate an IED (bomb)," the report said. "He shot the individual with his M-4 (assault rifle)."

ISAF later discovered that Khpulwak was unarmed and the shot which soldiers heard was probably fired by one of their own side.

The BBC asked NATO to investigate the incident last month after what it called "conflicting reports" emerged of the circumstances surrounding Khpulwak's death.

In response to ISAF's findings, the BBC said it was studying the statement and awaiting the full report into what happened.

"The loss of Ahmed Omed is a tragedy for his family and friends as well as his colleagues at the BBC," said Peter Horrocks, the director of BBC global news.

"Ahmed Omed's death further highlights the great dangers facing journalists who put their lives on the line to provide vital news from around the world."

Khpulwak worked for the BBC on a freelance basis and joined the broadcaster in 2008.