Naveed King has made an online appeal for financial support to help pay for the treatment of his five-year-old brother Ashya.
Speaking in English and Spanish, Naveed also thanked people around the world for their support so far which will be used to help his brother receive specialist proton beam therapy for a brain tumour.
The head of the police force which applied for a European Arrest warrant against the parents of Ashya King has now urged their release.
A British mother whose son's life was saved by proton therapy has told ITV that she defied NHS doctors' advice to pursue the treatment.
The parents of Ashya King said they took him out of a hospital to seek proton beam treatment which is not available under the NHS.