A proposed underground railway running beneath the heart of Islington and Hackney could bring £49billion in benefits to the capital, City Hall heard on Monday.

The £12billion Crossrail2 project, which is expected to stop at King’s Cross, Angel, Dalston and Hackney, would also reduce overcrowding and make train services more reliable, according to the London Assembly Transport Committee.

If it is agreed, the new railway would help ease congestion on the London Underground between Finsbury Park and King’s Cross – currently one of the most congested on the network with more than four people per square metre at busy times – as well as the London Overground. Valerie Shawcross AM, chair of the transport committee, said: “London needs a transport network that can cope with the millions of extra passengers that will travel on our tube and trains in future.

“The cost-effective investment needed to construct Crossrail 2 will herald sustainable rewards, potentially boosting London’s economy by up to £49 billion, not to mention bringing much-needed relief to passengers suffering on some of the UK’s most-crowded services.”

Crossrail 2 was put forward by business lobby group London First to handle the expected 1.5 million growth in population and 700,000 jobs created over the next 20 years.