TRADE UNIONISTS today called for an inquiry after it was announced that the opening of Crossrail will be delayed yet again.

Transport union TSSA general secretary Manuel Cortes criticised the “badly delayed” rail project, which Transport for London (TfL) has admitted may not open until December 2021.

TfL commissioner Mike Brown said that more time is needed to test trains on the new line — which is to be called the Elizabeth Line — before it can be opened to the public.

The earliest time that the trains can be tested is in July of this year.

This means that the line, which was meant to be operating by December 2018, will be delayed for at least three years.

The project has already faced a series of delays and severe problems related to uncompleted work at new stations and faulty rail equipment.

It is also estimated that it will cost around £18 billion to complete.

Mr Cortes said: “Long-suffering London rail commuters are going to have to wait even longer to enjoy the 21st-century services that Crossrail will provide, with even greater delays to the Heathrow section that will make such a positive difference to cross-London travel.

“Surely there must now be a full public inquiry into why the operation of this vital piece of infrastructure is so badly delayed.

“The people behind this mess — the private contractors which have let London down — must fully foot the growing bill for this delay rather than it being, as I fear, passed on to Londoners.”