LONDON (AP) — A British boy whose mother says he needs cannabis oil to prevent severe epileptic seizures is being treated in a London hospital while British officials review the case.

Billy Caldwell, 12, is in Chelsea and Westminster Hospital receiving treatment Saturday while his mother Charlotte Caldwell lobbies for the return of cannabis oil seized by authorities at London Heathrow Airport when she brought it back from Canada Monday.

She says the cannabis oil, which is banned in Britain, is the only substance that can prevent life-threatening seizures suffered by her son. She says the denial of the medicine by British officials is "beyond cruelty."

The Home Office said it is in contact with doctors treating Billy and is carefully considering treatment options.