A delayed London rail link, originally due to open last year, will start running in 2021, project bosses confirmed today.

Crossrail chiefs said the railway could still open in the first three months of the year, in line with revised predictions.

A new opening timetable will be announced in early 2020 – but project leaders today said they were “very confident” the line will open within 2021.

They also confirmed that costs will not increase further because of delays.

Crossrail is currently Europe’s largest infrastructure project, jointly funded by Transport for London and the Department for Transport (DfT).

Once complete, the new line will link Reading, Heathrow, and Essex to central London, with a branch to the south east of the city.

It was originally due to open in December 2018 and cost £14.8 billion – but the scheme has faced ongoing delays and escalating costs.This year, new leadership took over the project, with Tony Meggs appointed chair in January.

But Mr Meggs announced last month that the rail link would face yet more delays, and not open in late 2020, as he had originally hoped.

He also admitted project costs would increase by as much as £650 million, taking the total spend to over £18 billion.

This is on top of up to £750 million of lost ticket sale revenue caused by the delays.

But speaking at the London Assembly’s transport committee today, Mr Meggs said he was “very confident” that the line would open in 2021.

The chairman said Crossrail had been in “severe disarray” when he took over and his team had “since done a great deal” to improve its performance.

But he said more time was needed to develop software, and to test run trains on the line.

Mr Meggs said Crossrail “do not plan to ask for more money” as a result of further delays.

Project leaders are currently discussing funding with the DfT, to cover the £650 million cost gap, and projected revenue loss announced earlier.

The Mayor of London, Sadiq Khan, told the meeting he was confident that a new funding settlement will be agreed.

He said: “The relationship is a very good one – we are joint sponsors.

“The Crossrail board has the same candour with them [the DfT] that they have with us.

“I’m optimistic that we’ll reach a negotiation with the DfT that suits everyone”

He added: “Of course I share the frustration of Londoners that the Elizabeth line has not yet opened, and I apologise for this.

“But progress is being made, and we’ve already reached some very significant milestones in the last six months.”

Labour assembly member Navin Shah said the cost increases on the project had been “staggering”.

He said: “I’m somewhat reassured that the additional cost indication that you’ve made covers the overrun and the additional period required for completion.

“But I’m afraid we’ve heard this before in this chamber and again we have a situation where the cost has escalated.”

He added: “My worry is, could we be sitting round next year and looking at further cost increases on the project.”