Trump warns Iran against 'massacre' as protests erupt over plane downing

US President Donald Trump has said that the United States was monitoring Iranian demonstrations closely, warning against any new "massacre" as protests broke out after Tehran admitted to shooting down a passenger plane.

Iran said earlier it unintentionally downed a Ukrainian jetliner outside Tehran, killing all 176 people aboard, in an abrupt about-turn after initially denying Western claims it was struck by a missile. The firing came shortly after Iran launched missiles at bases in Iraq housing American forces.

President Hassan Rouhani said a military probe into the tragedy had found "missiles fired due to human error" brought down the Boeing 737,