KABUL, Afghanistan — The U.S.-led military coalition in Afghanistan says it has launched an investigation into allegations of misconduct by NATO troops in the country's south.

The coalition, known as the International Security Assistance Force (ISAF), said Wednesday that the probe pertains to an incident on April 28 during an encounter with insurgents in southern Afghanistan.

A statement from ISAF says four insurgents were killed in the incident. The NATO-led force did not disclose further details or elaborate on the allegations against coalition troops.

Afghan officials were not immediately available for comment.

The statement quoted American Gen. Joseph F. Dunford, the NATO commander in Afghanistan, as saying the alliance takes "all allegations of misconduct by our personnel very seriously" and would "fully investigate the incident and keep the Afghan government informed."