Tube maintenance firm Metronet may be in so much debt it could be difficult to sell, its administrators have said.
Metronet went into administration after a £2bn overspend
The firm could owe almost £1.6bn in debts to banks and London Underground (LU), its auditors believe.
Metronet is responsible for looking after nine London Underground lines but it went into administration in July amid serious financial problems.
LU managing director Tim O'Toole said Metronet was charging "premium" rates but it "failed to deliver".
Metronet had planned to invest £17bn over the next 30 years, under the terms of a public-private partnership (PPP) scheme.
'Rapid fire marketing'
Speaking at City Hall, auditors Ernst & Young said they may be forced to break up the consortium to sell Metronet.
Alan Bloom, from Ernst & Young, said: "We could determine that there is demonstrably value in what we have to sell, which is a PPP or two PPP contracts, which exceeds the value of the secured debt.
"It might do, if it does that then we will need to commence a very rapid fire marketing campaign in order to elicit expressions of interest," he said.
The Metronet consortium is made up of shareholders Atkins, Balfour Beatty, Bombardier, Thames Water and EDF Energy.
'Failed to deliver'
A further £1bn has been raised in bank loans, £1bn in bonds and £600m from the European Investment Bank.
Mr O'Toole, who was present at the meeting, said: "I definitely think the contracts did not match up with the work that was being delivered.
"We are trying to sort all this out and it is quite possible and I would hope that as we negotiate with some of these very same companies [part of the consortium] that they are able to come to an arrangement with us," he said.
A full valuation of the firm will be clear in the next two weeks.
TfL will have to take over Metronet if its administrators fail to sell it, Ernst & Young said.
'Jeopardise 2012 Games'
Previously London Mayor Ken Livingstone said he was keen to take over the company and may be putting in an offer soon.
Speaking at the TUC Congress in Brighton, The Rail, Martime and Transport Union (RMT) said Metronet's collapse could slow down the timetable to bring the Tube network to a suitable standard for the 2012 Olympic Games.
But Transport for London said the games would not be affected.
Last week more than 2,000 workers employed by Metronet went on a 72-hour strike saying the firm has failed to ensure their job security and pensions.
The RMT has warned of further strikes if the issues are not fully resolved.