The cancellation of the opening of a £30m railway line between Ebbw Vale and Cardiff only two days before it was due has been strongly criticised.
Safety and engineering issues are said to have delayed the launch
Safety and engineering issues are said to have held up the project, and it is now due to open in the New Year.
Transport Minister Ieuan Wyn Jones said Blaenau Gwent Council, responsible for the project, had assured him services would start before Christmas.
The council said it was "bitterly disappointed" at the delay.
The scheme would restore a rail line to the town after 45 years.
It would link an area hit hard by a decline in heavy industry with Cardiff.
An assembly government source told BBC Wales he spoke to a senior council official on Monday and was told: "We are not going to embarrass you. The railway will be 100% ready this week".
Blaenau Gwent AM Trish Law, an independent, said the cancellation "beggars belief" and described the announcement as a "bombshell".
She said: "If it was not such a deadly serious matter this would be the Christmas joke of all time.
"How can it be that we get an announcement like this just two days before the much-heralded official opening and 10 days before passenger services resume after an absence of 45 years?
"Who will finance the £2m of work that needs doing? There are many questions that demand answers."
The Ebbw Vale rail link scheme upgrades 18 miles of railway line for passenger services, restoring a link with Cardiff that was severed in 1962.
The project is a key part of the continued regeneration of the area following the closure of the Corus steel works in 2002.
Ebbw Vale's passenger rail link was severed in 1962
Mike German, leader of the Welsh Liberal Democrats, accused the assembly government of a "series of broken promises".
He said: "The government have simply never given the line top priority."
Plaid AM Jocelyn Davies said the delay was a "huge disappointment in the area and a complete embarrassment for the Labour council".
She said: "They've had years to get this line up and running, and now, a couple of weeks before Christmas, they let everyone down."
Robin Morrison, chief executive of Blaenau Gwent Council, said: "We were assured by all parties that the date of 22 December for commencement of services was achievable, and are bitterly disappointed that last-minute issues have forced a delay.
"The council's leadership and I are seeking a high-level meeting with all the organisations involved in the project to address outstanding concerns and deliver the service at the earliest possible date."