Warning: Graphic image

Muslim schoolchildren were targeted in an early-morning attack in Brisbane's south on Wednesday, when a bag featuring a swastika and containing a severed pig's head was left at a school's front gate.

Islamic College of Brisbane staff removed the bag before students arrived at the school in outer suburb Karawatha, acting school chairman Ali Kadri said, but staff and students had been left shaken.

"They're worried because, while it's a minor thing, there are really young kids who go to that school, because it goes from Prep to year 12," he said.