The Jubilee Line has been shutting on weekends since 2007
Months more weekend closures on the Jubilee Line are the result of the government's part-privatisation of the Tube, London's mayor has told MPs.
Boris Johnson told the House of Commons Transport Committee the problem "went to the heart" of what was wrong with the public-private partnership (PPP).
Maintenance firm Tube Lines will close the line about 28 weekends next year to complete the upgrade of the line.
The line has been regularly closed since February 2007 for the work.
The work has continually run over and earlier this year Mr Johnson said the reputation of Tube Lines hinged on its performance with the Jubilee Line.
Mr Johnson said the part-privatisation, which has already seen the collapse of the other private maintenance company, Metronet, was "a poorly conceived system" which had not operated in the interests of taxpayers or Londoners.
He added: "I don't think anyone in the Treasury now thinks PPP was the right model."
But he said that he was "not going to be tempted to read the last rites over Tube Lines or the PPP".
A Tube Lines spokeswoman had said earlier that the closures were unavoidable but would bring benefits for passengers.
The Jubilee upgrade has often led to the whole line being shut on weekend days, particularly affecting those attending events at the 02 Arena in Greenwich, south-east London.