Spain has begun excavating the sites where the remains of Republican soldiers killed during the Spanish Civil War are thought to be buried.

Since last week, bones, skulls and even black espadrilles have been turned up in the village in Piedrafita de Babia, near the town of Leon, north-western Spain.

Some seven sites near Piedrafita are being excavated in search of about 50 people, whose relatives say were killed on the night of 5 November 1937.

The Republican soldiers had been persuaded to turn themselves in to General Franco's nationalist forces which had taken over northern Spain.

A group called the Association for the Recovery of Historical Memory has been working for two years to identify and excavate mass graves which they say are dotted all over Spain.

The association uses the testimonies and memories of relatives and survivors to pinpoint the unmarked graves.

But the group believes that, as the graves are opened, more relatives will come forward.

"They are still afraid," said association spokesman Santiago Macias.

"They've been unable to speak for 60 years and it's an effort for them to break the silence. But they will."

Buried past

According to relatives, Piedrafita's mass grave was discovered the morning after the killings, but fear stopped the families from speaking out at the time.

"If you spoke once, you never mentioned it again. That was terror. On TV they go on about Yugoslavia, Chile, Argentina... they should ask us, we've suffered much more, and longer," said one.

Another relative, Asuncion Alvarez, 87, whose brothers were shot that night, became so worried over the years that their fate would be forgotten that she drew a map of the spot where they lay and gave it to her children.

Last week's excavations confirmed the map's accuracy.

One high-profile grave the association is hoping to locate is that of the poet and playwright Federico Garcia Lorca, who was shot and dumped in a trench in August 1936.