Guatemala's Constitutional Court has overturned the recent conviction and sentencing of former military ruler Efrain Rios Montt for genocide and crimes against humanity – a move that has appalled Amnesty International.

Sebastian Elgueta, Amnesty International's researcher on Guatemala, said:

"The ruling is a devastating blow for the victims of the serious human rights violations committed during the conflict

"The legal basis for the ruling is unclear, and it is uncertain how the trial court can hit the reset button to get back to a point in mid-April. What is clear is that the Constitutional Court has just thrown up formidable obstacles to justice and accountability for a harrowing period in Guatemala's recent history.

"With the sentence on 10 May, the trial court had sent a strong signal that crimes against thousands of Mayan victims would not be tolerated. The Constitutional Court has now questioned that message, putting the right to truth, justice and reparation at risk in Guatemala."