Plans to open the Elizabeth line this December will not go ahead.
The scheme, that is set to link up Woolwich and Abbey Wood to the underground, is now set to open in Autumn next year.
Crossrail sited safety concerns as the main reason behind the delay.
Greenwich council leader Danny Thorpe said: “We are bitterly disappointed that the Elizabeth Line will not be opening as planned this year, and I know that many of our residents will also be upset at this news.
“Abbey Wood and Woolwich have already started seeing the benefit of the “Crossrail effect”, with hundreds of news homes being built and businesses opening. This will continue, and I am sure that it will be worth the wait when it finally does open.”
The Crossrail project, which is the biggest infrastructure development in Europe, is running almost £600million over its £14.8billion budget.
When complete the line will run from Reading and Heathrow to Abbey Wood.
The line is already operating between Shenfield and Liverpool Street, and between Paddington and Hayes and Harlington.
An estimated 200million passengers are set to use the new underground line annually, increasing central London rail capacity by 10 per cent.
Mark Wild, London Underground and Elizabeth line managing director, said: “We will continue to work closely with Crossrail Limited as they complete the remaining railway infrastructure work and testing needed to deliver the new railway.
“The delayed opening is disappointing, but ensuring the Elizabeth line is safe and reliable for our customers from day one is of paramount importance.”
Simon Wright, Crossrail chief executive, said: “We have made huge progress with the delivery of this incredible project but we need further time to complete the testing of the new railway.
“We are working around the clock with our supply chain and Transport for London to complete and commission the Elizabeth line.”