VIENNA (REUTERS) - The cellar where Josef Fritzl kept his daughter captive for 24 years and fathered seven children with her is being sealed off with concrete, much to the relief of neighbours keen to forget one of Austria's most horrific crimes.

Fritzl, 78, was sentenced in 2009 to life imprisonment in a special unit for the criminally insane for incest, rape, coercion, false imprisonment, enslavement and for the negligent homicide of one of his infant sons.

"The dungeon will be filled with concrete and thus sealed at the family's request," estate liquidator Walter Anzboeck told Friday's edition of the Oesterreich newspaper.

The construction work began on Thursday and is expected to take a week, costing a total of 100,000 euros (S$169,000).

The idea is then to sell the house in the town of Amstetten in the province of Lower Austria, Mr Anzboeck told the paper.

Neighbours welcomed the news, though some said the house should be demolished.

"Hopefully it will quiet down again and Amstetten will no longer be known as the Fritzl town," Katharina Sitz, 34, told the Krone newspaper.

"There will always be crazy people who want to buy the house because of Fritzl. It should be torn down," said Oliver Michailov, 45.

Krone quoted an unnamed neighbour as saying: "They should cement Fritzl in there as well."

Fritzl imprisoned his daughter Elisabeth in the basement of the family home when she was 18. His wife, Rosemarie, reported her missing but Fritzl ordered his daughter to write a letter saying she had run away.

Three of the seven children he fathered with Elisabeth lived with her until they were freed in 2008. Fritzl and his wife fostered the other three surviving children after Fritzl claimed Elisabeth had given birth to them and then abandoned them to join a religious sect.

The Fritzl case followed the uncovering in 2006 of the Natascha Kampusch saga. Ms Kampusch was kidnapped at the age of 10 by Wolfgang Priklopil and held in a windowless cell under his house near Vienna for eight years before she escaped.