Victims of a baby-stealing policy approved by Francisco Franco's dictatorship demanded Friday that Spain's attorney general's office fully investigate the alleged theft of hundreds of newborns.

Three organisations that fight for the stolen children and their families delivered a petition with 89,666 signatures, calling on the attorney-general's office to stop shelving inquiries and reopen ones already closed.

Over 1,400 cases of newborn babies who were allegedly taken from their mothers in hospitals and ended up with other families have been filed with the office over the past year and most have been shelved, according to the petition organisers.

"We know that no one will give us back the time, and the part of our souls, which we have lost, no one can compensate parents who have not seen their son grow up, or those who have not been able to share their lives with a brother," said Soledad Luque Delgado, a spokeswoman for the petition organisers.

"But we should at least have the comfort of knowing the truth," she added.

Anadir, one of the three organisations behind the petition, estimates there could be as many as 300,000 cases of baby snatching during the 1939-75 dictatorship and up to the end of the 1980s.

Under a 1940 decree the state was allowed to take children into custody if their "moral education" was at risk.

The decree allowed the dictatorship to take children of jailed left-wing opponents from their mothers and have them placed with Catholic religious orders or adopted by ideologically approved families to purge Spain of feared Marxist influence.

Many of the same doctors, nurses and officials who carried out the Franco-era policy are accused of continuing it illegally after the dictator's death and Spain's return to democracy, as a business that provided babies for cash to women unable to give birth.

New mothers were often told their babies had died suddenly within hours of birth and the hospital had taken care of their burials when in fact they were given or sold to another family.

Teumila Dominguez, 64, was told her daughter was born deformed and had died shortly after she gave birth to her at a Madrid hospital in December 1973.

She was never allowed to see her daughter and has always suspected that the hospital put her newborn baby up for adoption.

"Whenever I take the metro I seek out the faces of young people to see if I spot my daughter," said Dominguez, who attended a protest outside the attorney general's office with her husband on Friday before the petition was delivered.

About 100 people took part in the demonstration. Many held up signs with the date of birth of their missing child or sibling and the name of the hospital from where they vanished.

Protestors chanted: "They did not die, they were stolen," and "Judges, look for them now," as a line of police guarded the entrance to the office.

"My mother is 85 years old. She still hopes to see her daughter," said Maria Carmen, 49, as she held up a sign that read: "I am looking for my sister."

"It is extraordinary that there has been silence around this issue for so many years."

Last year the attorney general's office rejected calls for a national investigation into the baby thefts on the grounds that those responsible were not part of a single network but operated from different parts of the country separately.

"Yes, children were stolen in Spain, but unfortunately we lack evidence to punish those who stole them," one public prosecutor was quoted as saying by El Pais newspaper on Friday.

"I don't believe that we are going to get it."