El Salvador's government has said it will cooperate in arresting 17 former soldiers who were allegedly involved in the killing of six Jesuit priests in 1989.

Prosecutors said the soldiers killed the priests to silence their criticism of the human rights abuses committed by the US-backed army in El Salvador's 1980-1992 civil war.

An estimated 75,000 people died during the war in total.

The government made the announcement on Wednesday after a Spanish judge sent a new petition to international police agency Interpol on Monday, ordering the soldiers' capture for the murders of the priests, their housekeeper and her daughter. Five of the priests were Spanish and one was Salvadoran. They were shot at their home at a university.

"The only path for our security forces to take is to proceed with the arrests, that is, there's nothing to do but follow the law," presidential spokesman Eugenio Chicas said in a statement to the media.

Among the officials wanted are Colonel Inocente Montano, a former deputy defence minister, who was arrested in the United States in 2011 for immigration fraud. US authorities said last April they would seek to extradite him to Spain.

Chicas said the extradition of the former soldiers to Spain would depend on El Salvador's supreme court.

Spain's high court ruled in 2011 that the ex-soldiers should be tried for the murders and ordered them arrested. Interpol also said the men were wanted for extradition.

But El Salvador's supreme court ruled then that Interpol had required the soldiers be located but not arrested or extradited.

"This is a new opportunity for the justice system in this country to put things right," said Omar Serrano, a vice-rector at the university where the priests were killed.

Additional reporting by Reuters.