Improvements to Britain’s railways must speed up as new figures show less than 40% of the network is electrified, a charity has claimed.

The Campaign for Better Transport (CBT) said a rolling programme of electrification is vital for the UK to meet its target of reaching net-zero carbon emissions by 2050.

Data published by rail regulator the Office of Rail and Road shows 156 miles (251km) of track was electrified in the year to March 31, due to work on the Great Western and West Anglia lines.

This brings the total amount of electrified track to 3,759 miles (6,050km), representing 38% of the network.

Separate ORR figures show 648 million litres of diesel were used by passenger and freight trains in 2019/20.

Running trains with electricity can cut CO2 emissions, boost journey times and reduce maintenance costs, compared with diesel.

But electrification plans in South Wales, the Midlands and the Lake District were axed or downgraded in July 2017 by then-transport secretary Chris Grayling.

The decision came amid cost overruns on projects such as the Great Western route, where the original budget was exceeded by around £2 billion.

Four new mainline stations opened in 2019/20, taking the total to 2,567.

They were: Meridian Water, north London; Robroyston, Glasgow; Warrington West, Cheshire; and Worcestershire Parkway, Worcester.

CBT chief executive Paul Tuohy said: “It’s great to see rail lines being electrified and new stations opened, but now we need to step up our game.

“Only 38% of the railway is electrified. We need a rolling programme of electrification to meet the Government’s net-zero targets.

“And too many communities are unable to access the rail network. New or reopened rail lines and stations could transform these places.

“Now more than ever, we need investment in rail infrastructure. Not just to enable more sustainable travel, but to create jobs, tackle social exclusion and help the economy to recover.”

Robert Nisbet, director of nations and regions at industry body the Rail Delivery Group, said: “Rail cuts up to 7.7 million tonnes of carbon emissions per year by reducing reliance on cars and lorries, but we want to go further to support Britain’s zero carbon commitments.

“That’s why we are currently investing in new bi-mode, hydrogen and battery-powered trains, and have proposed a long-term programme of electrification to improve performance and make our green way of travelling even greener.”

A Department for Transport spokeswoman said: “We are investing a record £48 billion to modernise, expand and decarbonise our rail network.

“Electrification will play a significant role in our programme to achieve our bold and ambitious vision for a net-zero carbon transport system by 2050.”