Crossrail will not open next year and its cost has increased by up to £650 million, the boss of the firm building London’s new east-west railway has said.

Mark Wild, chief executive of Crossrail Ltd, insisted services would begin “as soon as practically possible in 2021”.

He also revealed that the cost of the railway could reach £18.25 billion, representing an increase of between £400 million and £650 million on the latest funding commitment made in December 2018.

Crossrail’s budget was set at £15.9 billion in 2007.

It is being funded by the Department for Transport and Transport for London.

The railway was initially due to be completed in December 2018, but this date was missed due to a series of problems.

A new plan to open between October 2020 and March 2021 was announced in April.

Crossrail Ltd said there are four “major tasks” that must be completed before services can begin.

They are:

– Build and test the software to integrate trains with three different signalling systems;
– Install and test station systems;
– Complete installation of equipment in the tunnels and test communications systems;
– Trial run the trains for thousands of miles.

The railway will be known as the Elizabeth Line when it launches.

Mr Wild said he wants to “ensure reliability of the railway from day one of passenger service”.

He added: “We are doing everything we can to complete the Elizabeth Line as quickly as we can but there are no shortcuts to delivering this hugely complex railway.

“The Elizabeth Line must be completed to the highest safety and quality standards.”

The first part of Crossrail to open will be the central section, with trains running between Paddington and Abbey Wood via central London.

All stations on this section are expected to be in operation on the opening day except for Bond Street, which is delayed because of “design and delivery challenges”.

Full services from Reading and Heathrow in the west to Abbey Wood and Shenfield in the east will commence “as soon as possible”, according to Crossrail Ltd.

Caroline Pidgeon, who chairs the London Assembly’s Transport Committee, said: “The further delays to the opening of Crossrail and increasing costs are appalling news for Londoners.

“The delay creates huge issues for many businesses that have made investment decisions based on its original opening date of December 2018.”