The Spanish government has granted citizenship to 4,302 Sephardim whose Jewish ancestors were expelled from the country in 1492.
Under the new law, which was passed in June and came into effect on Thursday, successful applicants may retain their original nationality as well as becoming a Spanish citizen.
This first wave was fast-tracked under an old law which required incoming citizens to give up their former nationality, though these new nationals will not be required to do so.
Justice Minister Rafael Catala said the decision had been taken so applicants would not have to go through the process again.
