E-scooters are replacing more walks than car journeys in the region's controversial trial, figures reveal.

Cycling and walking charity Sustrans says it is concerned that the West of England Combined Authority (Weca) pilot project is not having the desired impact and is actually making many people less active.

Almost half of the trips that would have been taken on foot had the trial not been introduced were ridden on a Voi electric scooter.

But less than a third of drivers have left vehicles at home to hop on the new mode of transport.

Weca says more than 370,000 car journeys have been replaced since the start of the experiment in October last year, reducing more than 200 tonnes of carbon dioxide emissions.

It says 44 per cent of journeys would otherwise have been walked, six per cent bicycled and 31 per cent driven but that riders use e-scooters to go to gyms and leisure facilities.

There are no statistics yet for public transport, which is struggling to recover from the pandemic, but the combined authority says e-scooters are used to complement buses and train trips.

However, Sustrans' England South head of partnerships Jon Usher said: "While we support alternatives to using a car for short journeys in Bristol, this data shows that half of e-scooter trips in the city would have been walked or cycled before the trial was introduced – a similar outcome to what we've seen in e-scooter schemes across Europe.

"By swapping active travel for e-scooters, we're removing the health benefits that come from walking or cycling those journeys.

"This decline in physical activity will not only impact our health, but it can have an economic impact on the city."

Mr Usher, based in Bristol, said that in 2019 Sustrans' Bike Life, the biggest assessment of cycling in cities and urban areas across the UK and Ireland, found that the physical activity benefits of cycling alone in the city were valued at £94.6million per year.

"We want e-scooters to be more effective at replacing short car journeys, and for that to happen we need more investment in high quality, safe and attractive sustainable transport infrastructure," he said.

"For e-scooters to have a role to play in helping to reduce the amount of driving in Bristol, we need to commit to delivering the Citizens' Assembly recommendation of making 'Bristol the best city internationally to travel around, by prioritising sustainable, safe, healthy, accessible alternatives to the car for all by 2030'.

A Weca spokesperson said: "E-scooters are a new form of transport, and while there aren't many studies yet on their health impact, Voi has reported that riders use them to travel to parks, sports grounds, gyms and leisure facilities where they exercise.

"Research shows e-scooters are often used when time or distance is a factor.

"They are also used to complement public transport journeys – among the most popular spots to start and end journeys are near stations.

"Launching any new form of transport will inevitably see some trips migrate from other ways of travelling, however, it's important to remember that e-scooters are being trialled nationally to understand how they could form part of a wider transport network.

"We know that longer term the most important thing is to have a variety of sustainable transport options available.

"We continue to invest in alternatives to give people choices so they continue to replace car journeys to reduce carbon emissions and improve air quality."

Earlier this month, Bristol mayor Marvin Rees said the city council was pushing for the initial 12-month trial to be extended until the end of March next year because it had been an "overwhelming success", despite critics doubint its effectiveness and complaints over safety and parking issues.