Congestion on England's A-roads is getting worse, official figures show.

Traffic was delayed by an average of 44.7 seconds per mile compared to free-flow conditions for the year ending March 2016 – up by 4.2% on the previous 12 months.

The data published by the Department for Transport (DfT) also shows that average speeds have fallen by 2.1% over the same period to 25.5mph.

Congestion is growing faster in urban areas, with delays up by 4.9% and speed down by 2.7% in just 12 months.

Separate DfT figures show vehicles travelled an estimated 318.5 billion miles on Britain's roads in the year ending March, up 1.8% on the previous 12 months.

Car traffic was up by 1.3% while mileage by vans rose by 4.1% – faster than any other vehicle type.

Meanwhile the total length of roads last year was less than 0.1% higher than in 2014.

RAC roads policy spokesman Nick Lyes said that road usage was outstripping road space.

'Having a road network that is fit for purpose, in terms of being able to cope with increased traffic as well as being maintained to an acceptable level, is vital for a prosperous economy.

'There is little doubt that the government's road investment strategy recognises the importance of this, but these figures show there is a lot of catching up that must be done.'

Transport minister Andrew Jones said: 'The increasing number of miles vans are clocking up shows the economy is thriving, driven by the rise in internet shopping and home delivery.

'As our roads get more popular, our record £15bn investment is improving motorways and major A roads to make journeys better for all.'