UN Secretary-general Ban Ki- moon on Tuesday was appalled by the reported killing of four American hostages by Somali pirates, and called for more efforts to crack down on the criminal elements, said a note to the press from the UN spokesperson.

The note, issued following relevant press questions on Somalia, said: “The secretary-general is appalled by the reported killing of four American hostages on a yacht off the coast of Somalia.”

The Four U.S. citizens on the yacht were hijacked by Somali pirates last week, reports said.

Ban said that “piracy off the coast of Somalia is unacceptable, ” and he welcomes the ongoing efforts of the international community to stamp it out and bring the perpetrators to justice, the note added.