Last September TfL estimated it would cost £4.1bn to carry out improvements on the Tube between but Tube Lines say it will be £7.2bn.
A London Assembly reports believe that this disagreement is seriously slowing down work. Their transport committee chair, Val Shawcross, said: "Maintaining and upgrading the Tube is absolutely vital to the capital and Londoners have a right to know how it is progressing."
TfL is taking on projects following Metronet's collapse but around half of the 150 refurbishment plans that were supposed to be finished by 2010 have been delayed until 2017.
Departing, LU managing director Tim O'Toole said they had resubmitted their contract terms to Tube Lines, who have until June to respond. The BBC report said Tube Lines was unavailable to comment.
It will be interesting to see what happens when Tube Lines are available to comment. Val Shawcross, lives in South London, so knows all too well about the scarcity of the Tube south of the river, is right in pushing for updates. She said: "Any delayed or cancelled projects will have a real impact on people using the network."
I look forward to seeing the full report, which doesn't appear to be on the London Assembly's site yet. But I suspect that it might take a fair while to bridge the £3bn funding gap between TfL and Tube Lines estimations.
UPDATE - I've received an email from Tube Lines (who say they were available for comment) who sent me a copy of the report, which I'll digest later (it's also the London Assembly's site now). But in the meantime here's what Tube Lines said "We welcome the findings of the London Assembly's report and the importance it places on having the right levels of funding in place to ensure London has the Tube service it needs in 2010 and beyond.
"It rightly notes that we are a well managed business that is successfully delivering vital improvements to the Tube. We can also demonstrate that we are delivering the work in a cost efficient manner, and in many instances are delivering at lower costs than many international metro systems.
"There is still so much more to do on the Tube, particularly with regards increasing capacity for passengers and we therefore hope that the funding that is needed to achieve this continues."