Plans for a rail link between the Great Western mainline and Heathrow Airport will be delayed by up to two years.
A planning application for the long-anticipated scheme, which would allow people living to the west of Heathrow to travel direct to the airport, had been expected this year.
But Network Rail said the proposal had been delayed by the impact of Covid-19.
Reading Borough Council's lead for transport Tony Page described the delay as "deplorable".According to the £900m proposal trains would run every 15 minutes from Reading to Heathrow, with a journey of less than half an hour.
Currently rail passengers from the Thames Valley, Wales and the West have to travel via London.
Network Rail said a Court of Appeal ruling and the pandemic's effect on the aviation industry had delayed the Department of Transport's progress with the Nationally Significant Infrastructure Project - which requires a Development Consent Order (DCO) for planning permission.
They said in a statement: "The Department has been clear that whilst it fully supports the development of a Western Rail Link to Heathrow, this is subject to a satisfactory business case and the agreement of acceptable terms with the Heathrow aviation industry."
The DCO is expected to be submitted next winter.