The MPs predicted that the public–private partnership would lead to "expensive disputes over the contracts and between staff and employers", and said it was disgraceful that the Health and Safety Executive had been given only one month to decide whether the latest scheme was safe.
The report was endorsed by Transport for London boss Bob Kiley, who has consistently opposed the PPP.
He said: "The committee's report highlights many flaws: the scheme is potentially unsafe, it creates a fragmented underground system and it is hugely expensive."
Transport secretary Stephen Byers countered the MPs' findings by stressing the urgency of upgrading the London Underground Tube network.
He said: "Now is the time to take decisions about how to get the investment in. Delays and cancellations just get worse. Londoners cannot wait any longer."
Byers, who is undertaking a review of the PPP is expected to decide in support of it.
If he does, the final deal with preferred Tube bidders, Tubelines and Metronet, will be signed in May.