MEXICO CITY, April 19 (Reuters) - Mexico's defense minister will face lawmakers next week who suspect the army covered up a reported rape and killing by soldiers of an elderly peasant woman.

Opposition legislator Pedro Montalvo said Mexico's top human rights official would also appear in Congress to answer questions about the death in February of 73-year-old indigenous grandmother Ernestina Ascencio a few hundred feet from an army camp in the state of Veracruz.

"This affair has polarized every government institution," said Montalvo, who sits on the house defense committee and is represents the poor mountain region where Ascencio lived.

Her death became a national scandal after the army, headed by Defense Minister Gen. Guillermo Galvan, made contradictory statements about what had happened.

The confusion was compounded when President Felipe Calderon said the attack had never happened, and that Ascencio had died of chronic gastritis.

Family members say before her death Ascencio told them she had been raped by a group of soldiers.

That version of events was supported by post-mortem examinations by Veracruz attorney general's office, which said Ascencio had died from injuries sustained during the attack.

Jose Luis Soberanes, the rights ombudsman, said the initial post-mortem examinations were full of errors and that a subsequent autopsy showed Ascencio had died of natural causes.

The army first claimed she had been killed by criminals dressed as soldiers, then said it was testing semen taken from Ascencio's body to see if it matched the DNA of soldiers stationed near the village where she died.

The defense ministry now says it never received the semen sample from Veracruz investigators.

Montalvo said people in Ascencio's village of Soledad Atzompa wanted the case cleared up.

"They don't want to see more contradictions in the army and they don't want this to keep happening," he said.

Mexican soldiers are regularly accused of rape in remote regions of the country, where the army is deployed to fight drug smugglers.

Calderon has sent thousands of troops to crime hot-spots and rural areas of the country to clamp down on powerful drug gangs.

Lawmakers will also question the defense minister about other themes, including the fight against drug smugglers.

AlertNet news is provided by