Madrid - About 30 per cent of Spaniards may have ancestry among Jews and Muslims who lived on the Iberian Peninsula before being expelled centuries ago, press reports said Friday.

The reports quoted a study by geneticists from the universities of Pompeu Fabra in Barcelona and of Leicester in Britain, published by American Journal of Human Genetics.

The study analyzed the Y chromosomes, which pass relatively unchanged from father to son, of 1,140 Spanish males around the country.

The structure of the chromosomes was compared with that of north Africans in Morocco, Algeria and Tunisia, and with that of Sephardic Jews living around the Mediterranean.

Nearly 11 per cent of the Spaniards showed common genetic characteristics with north Africans and nearly 20 per cent with Jews.

The Jewish genetic component could, however, have become overrated in the study, one of its authors, Francesc Calavell, conceded.

Other Middle Eastern populations share the same genetic signature, which could also have been brought to Spain earlier by non-Jews such as Phoenicians.

The first Muslims known as Moors crossed over to Spain from North Africa in 711, when Jewish populations had already settled on the Iberian Peninsula.

Muslims ruled parts of Spain for eight centuries until 1492, when Catholic monarchs Ferdinand and Isabella completed what is known as the Christian reconquest of the country.

All Jews who refused to convert to Christianity were ordered to leave that same year, and all Muslims who did not convert where expelled in the early 17th century.

The number of expelled people is estimated at hundreds of thousands.

The amount of Spaniards with Muslim and Jewish genes indicates that there were more conversions than had earlier been believed, according to the study. (dpa)