A fundamental review of the way Britain's railways are run has been announced by the government.
New regional controllers may have powers to run both tracks and trains.
Transport Secretary Alistair Darling told MPs the changes were needed to streamline the over-complicated structure since privatisation.
Analysts have talked of the plans meaning "creeping renationalisation".
Conservative transport spokesman Theresa May said the latest review was about "increasing centralisation and political control".
She said passengers were seeing no improvements despite five changes in the rail network's structure since Labour first won power.
In his statement Mr Darling said that the rail network had been left fragmented, excessively complex and dysfunctional due to privatisation under the previous Tory government.
But he warned that the government did not favour renationalisation because it would not solve the network's problems.
Mr Darling also made it clear that there would be a continuing role for the Strategic Rail Authority and its chairman Richard Bowker. That followed speculation that the SRA chairman would be forced to quit.
Weekend newspaper reports predicted Mr Darling was preparing to strip the
SRA of much of its powers, amid concerns over its effectiveness.
The body is responsible for overall development of the railways and regulating passenger services.
Mr Darling also outlined a review of the way safety matters were monitored and indicated the current system would be rationalised.
He also made it clear that the current structure was hampering effective decision-making and often led to "unnecessary wrangling and disputes".
That was in part due to there being "too many organisations, some with overlapping responsibilities".
Chairman of the Commission for Integrated Transport, Professor David Begg, warned it would be a "retrograde step" to sideline the SRA less than four years after it was created.
Professor Begg - who is a board member of the SRA - said the authority was created to provide leadership to a very fragmented industry.
But Bob Crow, general secretary of rail union RMT, called on transport secretary Alistair Darling to "bite the bullet and scrap the SRA".
There is also understood to be concern about the performance of two other rail agencies - the Rail Regulator and Network Rail.
Rail analyst Christian Wolmar told BBC News it was hard not to see the latest shake-up as another chapter in "creeping renationalisation" of the railways.
"We are moving back towards creating some sort of funny hybrid in which the state is largely in control," he said.
But Mr Darling said: "No government department can or should attempt to operate the railways".