London’s £15bn Crossrail project is to open nine months after its scheduled launch to allow more time for testing.

Europe's biggest infrastructure project will help ease London's chronic congestion by connecting major landmarks such as Heathrow Airport and the Canary Wharf business district.

The route, to be known as the Elizabeth Line, had been due to open in December, but will instead be launched in autumn 2019.

It is running almost £600m over budget and extra funding was required.

When fully operational, trains will run from Reading and Heathrow in the west through 13 miles of new tunnels to Shenfield and Abbey Wood in the east.

It will operate as three separate services - as previously planned.

Crossrail says the new line will connect Paddington to Canary Wharf in 17 minutes.

An estimated 200m passengers will use the new undergound line annually, increasing central London rail capacity by 10% - the largest increase since World War Two.

Crossrail Limited described the 10-year project as "hugely complex".

The original timetable for testing has been reduced by contractors needing more time to complete work in the central tunnels and develop software, Crossrail said.

Transport for London (TfL) said more time is needed "to ensure a safe and reliable railway for customers from day one of passenger service".

Simon Wright, Crossrail chief executive, said: "The Elizabeth line is one of the most complex and challenging infrastructure projects ever undertaken in the UK and is now in its final stages.

"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."

Elizabeth line trains are already operating between Shenfield and Liverpool Street, and between Paddington and Hayes & Harlington.