Plans costing £3 billion to renovate the crumbling stonework of the Houses of Parliament could see MPs and peers temporarily moved out of their historic home.
A panel of experts has drawn up a series of options for carrying out the work, following warnings the Palace of Westminster may have to be abandoned altogether unless it undergoes major renovation.
But one report suggested that the bill could double to around £6 billion if MPs refuse to vacate the building and insist on the work being done around them.
It is thought that the report, commissioned by the Palace of Westminster authorities, could suggest that MPs and peers leave the building for up to five years while the renovation takes place.
It would mean relocating to another venue such as the nearby Queen Elizabeth II Conference Centre or Westminster Central Hall.
Many MPs, however, are deeply reluctant to leave and the Leader of the Commons Chris Grayling said last week the the building remained "a vital heart to our democracy".
The restoration required is so vast because of the piecemeal way repairs have been carried out since the 1940s when the Palace of Westminster was bombed during the Second World War.
A report in 2012 found crumbling stonework, iron roofs rusting and leaking and toilets that flooded, while the building is stuffed with asbestos.
The current building was largely constructed in the 1840s and 1850s after the previous Palace of Westminster burned down in a fire in 1834 and is now a World Heritage Site.