The true scale of asbestos in the Palace of Westminster is so vast that MPs were in danger of inhaling the lethal substance, according to a report which recommends that MPs and Lords decamp for six years, the Times has reported.

The mother of parliaments is so “riddled with asbestos” that the dangerous building material can be found in almost every shaft holding the palace upright, the report says.

MPs from the restoration committee have been deciding how best to renovate the building safely and cheaply. The prevalence of asbestos has added “greatly to the complexity, cost and timetable” of the works and helped to persuade the group that politicians must be moved out for six years while the renovation takes place.

The report proposes moving MPs in 2022 to Richmond House, a building next to the parliamentary estate and now occupied by the Department of Health, and moving the Lords to the Queen Elizabeth II Conference Centre. State ceremonies could take place in the Banqueting House, Buckingham Palace or Westminster Abbey.

The committee said that it was unable to issue a new figure for how much the works might cost, and repeated estimates from 2014 of between £3.5 billion and £4 billion. Baroness Stowell of Beeston, who co-chaired the committee, said that an appropriate authority should be set up immediately to set a budget to be presented to both houses of parliament.

The report focuses on the issue of asbestos, which “is believed to be in almost every vertical riser, as well as in many plant rooms, corridors and underfloor voids”.  The report adds;

“One example of the danger posed by asbestos was brought home in 2015 when it was thought that asbestos fibres might have been present in the air provided to the House of Commons chamber. During upgrade work on one of the air ducts which supplies air to the chamber, a small section of duct was removed and asbestos dust was found to be present within it.”

Although tests later showed the risk to MPs was negligible in that instance, the report warns: “If the results were different next time and asbestos fibres were found to have contaminated air ducts, it is easy to see how one of the chambers, committee rooms or other essential offices might have to be closed down immediately and could be out of action for a significant period of time.”

The committee has also detailed the likelihood of a “complete loss of electrical power to one of the chambers, a devastating fire, extensive flooding, or a gas leak” in the near future while warning that the lack of any “fire compartmentation means the risk of a major conflagration spreading throughout the building is always there”.

Lady Stowell admitted that the multibillion-pound works were a “hard sell” but suggested that politicians had no other option to save the building while keeping it as a parliament.

The recommendations will be presented to both houses for a vote before the government decides what steps should be taken.

A No 10 spokeswoman said yesterday that the prime minister had not seen the full report and had not come to a decision on whether to support the recommendations. Earlier in the week committee members were told that Theresa May had not opposed the plan after an informal consultation.