JOHANNESBURG: More than 70 people were killed overnight when fire raged through a five-storey Johannesburg apartment block that may have been rented out illegally, known as a "hijacked building":

WHAT ARE HIJACKED BUILDINGS AND WHEN DID THE ISSUE BEGIN?

Since the end of apartheid in 1994, a housing crisis in South Africa's largest city of Johannesburg, in Gauteng province, has grown worse, as big businesses moved out of the inner city into affluent suburbs.

Criminal syndicates in the 1990s and 2000s started "hijacking" buildings that were left empty and renting them out illegally. They quickly became dilapidated centres of drugs crime and other lawlessness.

In some instances, the syndicates occupied buildings with fraudulent title deeds, said Angela Rivers, general manager at Johannesburg Property Owners and Managers Association.

People living there were convinced of the criminals' ownership and either paid rent or were pushed out, Rivers said.

HOW BIG A PROBLEM IS THE HOUSING ISSUE?

At least 1.2 million people in the province are homeless, a provincial official said on Thursday. Rivers said she was aware of 57 known hijacked buildings in the Central Business District alone, mostly owned by the city or the provincial government.

Experts say such buildings are prone to hijacking as they are badly managed with little access to amenities such as running water and electricity.

The gutted building on Thursday was owned by Johannesburg city, Mayor Kabelo Gwamanda told reporters. The city had leased it to a charity but it had "ended up serving a different purpose", he said without giving details.

Many dilapidated buildings in the inner city are occupied by people who earn less than 3,500 rand ($190) a month and account for over half of those living in the area, said Edward Molopi, senior communications and advocacy officer for Socio-Economic Rights Institute.

They look for housing that is closer to work opportunities, and the municipal government has to respond to their housing needs, he said.

Many also lack proper documentation to stay in formal housing and working in informal jobs means they have no way of getting any kind of official ID papers.

WHAT HAS BEEN DONE TO DEAL WITH THE ISSUE?

Lebogang Isaac Maile, the head of the Human Settlements department for Gauteng province, said 23 hijacked buildings had been identified in Johannesburg as in need of development. About 100 buildings had no apparent owners.

"There are cartels who prey on who are vulnerable people. Because some of these buildings, if not most of them, are actually in the hands of those cartels who collect rental from the people," he told reporters.

He did not elaborate on how authorities intended to solve the issue.