Tube maintenance firm Metronet has been criticised for its performance by an independent assessment.
Mayor Ken Livingstone has been highly critical of Metronet
The company has not performed in an economic and efficient manner over the last three years, the Public Private Partnership (PPP) Arbiter said.
Metronet has been chastised in recent months for falling behind on its track maintenance and renewal projects.
The firm defended its record and said the report found it generally performed "at or better than benchmark".
The assessment covered the firm's activities since the PPP agreements were introduced in April 2003 and March 2006.
PPP arbiter Chris Bolt, author of the report, concluded Metronet had not "performed in line with the required standard over the period as a whole".
He said Metronet had poorly planned some of its work and said management "deficiencies" were hindering the delivery of its PPP obligations.
He said it had taken measures to address "shortcomings in its performance" in the last year that have helped to improve standards.
But he said the benefits of those changes have yet to be felt, and "areas of weakness remain" including:
- Stations, where Metronet is significantly behind schedule in delivering its obligations
- Tracks, where there have been insufficient resources to deliver required volumes of work and poor delivery of maintenance and renewals
"While Metronet is demonstrating good performance in some areas, such as fleet management, it needs to make significant improvements in other areas," said Mr Bolt.
'Failing to deliver'
Mayor Ken Livingstone said the report showed that "Metronet is failing to deliver the quality and efficiency for which it is being very generously paid under the PPP".
Andrew Lezala, Metronet chief executive, said it recognised the firm's performance "has fallen short of expectations in some areas".
"We intend to ensure that appropriate improvements will be made in good time to be economic and efficient in advance of the end of the first contract period in 2010."
Bob Crow, general secretary of the Rail Maritme and Transport union, urged the government to scrap PPP.
"Failure is built into the very fabric of the PPP and it has to be ended," said Mr Crow.