The cost of renovating the Dutch parliamentary complex is expected to balloon to €2 billion, more than four times the original estimate, home affairs minister Hugo de Jonge has told MPs.

De Jonge said the costs were “unavoidable” because the estate was in a much worse condition than originally estimated.

More asbestos has been found, several walls and ceilings have rotted and the water from the lake on the north side is leaking into the Senate building.

In his 11th progress report, De Jonge said the total budget for repairs and renovations so far amounted to €1.65 billion – nearly double the most recent estimate of €844 mln and up from an initial estimate of €475 mln in 2015.

“In total we should allow for a total sum of €2 billion for the renovation”, he added.

The Binnenhof complex is the oldest monumental structure in the Netherlands, comprising 4,000 rooms over an area of 90,000 m2, parts of which date from the 14th century.

“This renovation will preserve this magnificent monument, the oldest centre of government in the world, for the future,” De Jonge said.

Rising costs of labour and materials have inflated the price and the project has also been extended for a year to 2028, by which time MPs will have spent seven years in the temporary parliament building on Bezuidenhoutseweg.

The renovation was also delayed because the government took longer than expected to obtain an environmental permit and because of the need for extra security measures, such as building a fortified bunker for the heating, cooling and electrical installations.