When the persecution of the Jews of Hungary was at its peak, starting May 1944, similar to other diplomats of neutral countries, stationed in Budapest, Sans-Briz sought to protect Jews which in his case claimed a Spanish origin. He based his humanitarian action on a 1924 Spanish law which promised Jews of Spanish descent a restoration of their citizenship. To save them from deportation, he issued protective passports, which were documents certifying that the persons wee under the protection of Spain until such time as it was possible for them to proceed to Spain. In the meantime, many of these persons were sheltered in special homes flying the Spanish flag. It is estimated that close to one thousand Jewish persons were saved through the help of Sans-Briz.
Sources: Yad Vashem