Police in the northern Nigerian state of Kano have rescued a 55-year-old man who was locked up by his family for 30 years because he was apparently mentally ill, human rights activist Sani Shuaibu has told the BBC.

The man had suffered for decades, one of his feet bound by a metal bar to a heavy log in a room without a door and window, Mr Shuaibu of Human Rights Network (HRN) said.

He alerted police about the man's plight following a tip-off, and joined the operation to rescue him from a property in Rogo town.

“He has some mental issues and was becoming aggressive and instead of seeking help in 1990 the father decided the best thing to do was to lock him up," Mr Shuaibu told the BBC.

“When the father died some years ago his two brothers, both younger than him, continued with the detention but today he is a free man. Some neighbours aware of his situation were key in this rescue,” he added.

The 55-year-old is currently at Rogo General Hospital where he is receiving treatment, while his brothers have been taken in for questioning by police.

Kano Police Command spokesman Abdullahi Haruna confirmed the rescue to the BBC and said they were investigating the case.

This is the third high-profile rescue operation in less than two weeks of people with special needs detained by their families.

HRN, a non-governmental organisation, was involved in all three rescue operations. Its head, Comrade Haruna Ayagi, told the BBC that more cases should be expected because it was "a deep-lying issue that has been ignored for long”.

“In most of these cases, the parents were blessed with children with special needs and since they have no resources to take care of them and no help from government or institutions, they resort to locking them up,” he added.