Sources at the teams said closing a line for six months to a year could halve the time and cost of upgrading and maintenance work.
Under the present PPP contract, the consortiums have to carry out work in the four hours each night when the Tube is closed.
One consortium source said the forced closure of the Central Line after a crash at Chancery Lane in February had strengthened the argument for line closures. The source said: "The Central Line was closed for many many weeks and London didn't grind to a halt. You could do work for half the cost and half the time during closures rather than just overnight."
The closures, which are guaranteed to be met with fury by commuters, would be unlikely until 2010.
One source close to London Underground said the closures would be a challenge for the logistical and administrative skills of the consortiums. He said it may take up to a year to draw up a detailed plan for a closure.
The fact that whole-line closures were under consideration was confirmed by both consortiums and Transport for London, the quango that took control of London Underground from the government on Tuesday.
There could be big benefits to everybody if this was to be considered
Metronet said: "We are very happy to contribute to the thinking about closures – we gave it some thought during bidding. There could be big benefits for everybody if this was to be considered." Tube Lines said it would consider "any approaches" that would deliver improvements.
According to TfL, transport commissioner Bob Kiley had not ruled out changing clauses of the PPP contracts to permit whole-line closures.
TfL said it was looking to attract extra funding, in addition to money from the consortiums and government, for additional work on the Tube system.
It has also emerged that the proposed £10bn CrossRail development (see factfile) will involve closures at five of London's busiest Tube stations for up to six months.
London must wait 13 years for CrossRail’s second lineThe second line of the Cross London Rail Link – CrossRail – will not be operational until 2016, it has emerged.
The government this week gave qualified support to the west–east CrossRail 1 scheme, which should be ready by the end of 2012. When public consultation starts on CrossRail 1 later this year, the scheme’s parent company, also called CrossRail, will work on details for a north–south line, to be ready four years after its sister line.
A spokesperson for CrossRail said: “We will be returning to work on CrossRail 2 later in the year; this includes consultation, preparatory engineering work and building up a business case.”
The first line, running east–west, is expected to go through the legislative process from November next year.
To avoid tying itself to an inflexible deadline, the government has said that CrossRail will not be ready in time for a London Olympic Games in August 2012. Bernard Gambrill, head of public affairs at CrossRail, said: “We believe it would be an intolerable burden to get the project delivered so quickly – the experience of the Jubilee Line shows that we shouldn’t do that.”