A Japanese couple have been arrested after their 33-year-old daughter was found frozen to death in a tiny room where they had kept her under lock and key for at least 15 years, wrote dailymail.co.uk.

Police in Osaka said the body of Airi Kakimoto's was found in a state of extreme malnutrition, weighing just 19 kg after her parents reported her death on Saturday.

Yasutaka Kakimoto, 55, and Yukari Kakimoto, 53, have allegedly confessed to feeding her only once a day and confining her in a 3-square-meter room.

'Our daughter was mentally ill and, from age 16 or 17, she became violent, so we kept her inside the room,' police quoted her parents as saying.

People with mental and physical disabilities - and their families – are often stigmatised in Japan despite recent efforts to change public attitudes.

Police say that Airi's room was monitored by numerous cameras and had a double door that could only be unlocked from the outside. It contained a makeshift toilet attached to a water tank outside.

Other surveillance cameras were also in place outside the single-story home, which was surrounded by a 2-meter high fence.

Airi is believed to have died around 18 December.