The coalition statement said that the strike was requested by the partnered forces, which had identified the target location as an ISIS fighting position. (Photo: Representational/AP)

Washington: A US-led coalition air strike in support of local forces fighting the Islamic State group in northern Syria accidentally killed 18 of the friendly fighters, the coalition said on Thursday.

"The strike was requested by the partnered forces, which had identified the target location as an ISIS fighting position," a coalition statement read.

"The target location was actually a forward Syrian Democratic Forces fighting position." The strike occurred south of Tabqa on April 11.