Israeli police have freed a 14-year-old boy who looked "like a zombie in a horror film" after he spent most of his life captive inside a locked apartment.

The boy came to the attention of police after neighbours in the northern city of Hadera reported a stench from the property, which was sealed off with a makeshift cage.

Police reportedly arrived at the property expecting to find a corpse, but after breaking in through a window discovered the boy, who was taken to the Hillel Yaffe Medical Center for treatment.

He was then transferred to social services, where it emerged he had been held captive by his parents for most of his life.

The only time he was allowed out was once every two weeks, when his parents took him into the caged enclosure of the property for half an hour at a time.

Police later detained the parents, who are said to have moved to Israel from Russia in the 1990s.

Birth was never registered

According to documents analysed by Haaretz, the parents never reported the existence of the boy or attempted to register him with any educational facility.

The director of the Hadera environmental department, Yitzhak Buzaglon, told Haaretz that the boy was discovered with dishevelled hair and clothes that were clearly too small for him.

The apartment was also filled with refuse and junk, leading to assumptions that the parents suffered from compulsive hoarding disorder, said Buzaglon.

"I've worked at city hall for 20 years," he added, "but I have never encountered such a thing."

Dan Gilad, the mother's public attorney, said his client claimed "that she acted out of concern for her son, who suffers from medical problems, and that the boy was in fact receiving medical care".

Police said that they "intend to continue investigating the circumstances of the incident".