Prosecutors in Madrid are seeking a 150-year jail sentence against Inocente Montano for the "terrorist assassination" of the six men, their cook and her 16-year-old daughter. Five of those killed were Spanish.

Montano, El Salvador's deputy minister for public security (1989-92), is the first of the accused to face trial after Spain launched inquiries in 2009 on the principle of universal justice.

The authorities in El Salvador have refused to hand over other military officers to Spain.

But Montano was extradited to Spain from the United States in 2017, where he had served nearly two years in jail for immigration fraud. He has been held in custody since then pending trial.

Prosecutors say the officers decided on, planned and carried out the November 16, 1989 killings.

They argue that they were part of a "parallel structure at the heart of the Salvadorean state" operating illegally, and "causing a state of terror within the population".

It was Montano, they said, who gave the order for the Jesuits to be killed.

The religious order acted as an intermediary between the government and FMLN guerrillas during efforts to start peace talks.

Montano, who is now 76, had been due to be tried with Rene Yusshy Mendoz, who served as a lieutenant in the Atlacatl battalion that carried out the killings.

But he was acquitted on Monday after the defence argued successfully that by the time he was charged the alleged crimes were past the statute of limitations.

The trial resumes Wednesday with the questioning of Montano and is expected to run until July 16.

The civil war in El Salvador ended in 1992 with a peace accord after 12 years of fighting between the government and rebels in which more than 75,000 people died and 7,000 disappeared.