A historical association called Monday on the government to posthumously award one of Spain's highest honours to a Japanese man who helped exhume the remains of people who went missing during Spain's civil war.

The Association for the Recovery of Historic Memory, which works to help Spaniards locate the graves of loved ones who went missing during the 1936-39 conflict, said the late Toru Arakawa should be awarded the Order of Civil Merit in a letter sent to Prime Minister Jose Luis Rodriguez Zapatero.

In the letter, the president of the association, Emilio Silva whose grandfather was executed by General Francisco Franco's forces during the civil war, said Arakawa had "carried out an extraordinary service for our benefit".

"For people who got to know him in the various towns where he worked it was especially moving to see someone from so far away invest his time and money to come and repair the terrible damage that a family member of someone who disappeared suffers from," he added.

Arakawa, a former English teacher, traveled to Spain for the first time in 2006 to help the association with its exhumations of mass graves after reading about it in a newspaper in his hometown of Niigata in central Japan.

He returned for two other two-month spells in Spain to help with the exhumations before his death in October 2009 at the age of 70.

The Association for the Recovery of Historical Memory has carried out over one thousand exhumations since it was set up in 2000, mostly using its own funds.

It estimates that as many as 114,000 Spaniards were killed or disappeared during the civil war which pitted Franco's right-wing forces against an elected left-wing government.

The war ended with Franco's becoming a dictator and ruling Spain until his death in 1975.

While Franco's regime honoured its own dead, it left its opponents buried in hundreds of unmarked graves across the country, which are only now being unearthed with the encouragement of Spain's Socialist government.