The US-led coalition in Afghanistan has apologised for mistakenly killing a two-year-old boy during an airstrike, the latest crisis to confront American officials hoping to finalise a long-term security agreement between the two countries.

Afghan President Hamid Karzai had blasted the US military for the death and accused coalition troops serving in Afghanistan of ''oppressions.'' Within hours, US and coalition military leaders were rushing to try to control the fallout of the strike, which also wounded two women.

General Joseph Dunford. Credit:AP

Marine General Joseph Dunford, commander of US and coalition forces in Afghanistan, called Mr Karzai to apologise personally.

The international coalition also issued a statement saying it ''deeply regrets'' the incident.