The Inter-American Court of Human Rights has ruled that El Salvador should reopen its investigation into the army's killings of around 1,000 people during an infamous civil war-era massacre and pay restitution to the victims' relatives.

The court said in Monday's ruling that the 1981 killings in and around the community of El Mozote in eastern Morazan province were part of a "systematic plan of repression" by the military during the Central American nation's conflict. The court also referred to "diverse violations suffered by the surviving victims," including destruction of property and arbitrary jailings.

Based in San Jose, the court is an autonomous judicial institution that works with the Organization of American States.

In December 2011, the Salvadoran government apologized for the massacre during a ceremony in the town.