Successive Tory-led governments have been accused of squandering the sporting legacy left by the 2012 Olympics in London, amid evidence that falling amounts of school time are being used for PE, and a third of children in several parts of England are active for less than 30 minutes a day.

Official figures show that the share of school hours spent on PE has suffered from a slow and steady decline since 2013, from 8.4% of school time to 7.7%. New figures also reveal that, heading into the pandemic, about a third of children and young people in London, the north-west, the West Midlands and Yorkshire and the Humber were active for, on average, less than 30 minutes a day, according to Sport England.

This comes as Labour councillors across the country have written to the government, warning them that they are “failing to support our Olympic legacy” in providing access to sport for the young. They warned that significant cuts to local government since 2010 had left “a tangible difference when local authorities are responsible for a third of swimming pools and 31% of grass pitches”.

The councillors, including leaders in Newcastle, Cardiff, Norwich, Knowsley, Stevenage and Sheffield, write: “We have therefore seen a widening of the activity gap and, most recently, an admission from the government that teaching time for PE in state-funded schools has fallen since 2011 when it should have been going up.

“Everyone should be able to join in regardless of where they are from or what party runs their area. At the moment, we know this is not the case, with more than 30% of children and young people reaching only 30 minutes of physical activity a day in the east, east Midlands, London, north-west, West Midlands and Yorkshire and the Humber regions. We need a comprehensive plan for health and wellbeing, and grassroots sport participation across the country must be central to that plan.”

Figures released through parliament have already shown that the number of PE teachers is down from 26,005 in 2011 to 23,513 in 2020. The criticisms coincide with the end of another successful games in Tokyo for Team GB. Alison McGovern, the shadow sport minister, said that a new “comprehensive strategy” was needed for grassroots sports. “Local authorities can’t do it alone and they’ve had a difficult decade as it is, stretching thinner resources further,” she said. “It’s time the government steps up and makes sure another great summer of Olympic inspiration doesn’t go to waste.”

Guidelines from the chief medical officer state that children should be active for an average of 60 minutes every day, with 30 active minutes taking place within the school day. Despite a drop in the minutes schools are offering, officials said they were still reaching the 30-minute target.

“We want every child to enjoy the benefits of sport, and our continued investment in PE is playing an important role as we recover from the pandemic,” said a Department for Education spokesperson. “We recently announced the continuation of the GBP320m PE and sport premium, boosting sporting opportunities for millions of children across the country, and supporting higher quality PE lessons.”

Ministers had already been criticised after accusations that they had slashed grassroots sport funding by nearly half since coming to power. Labour said it spent more than GBP1bn on sport and recreation facilities during the financial year ending in 2010, representing GBP1.24bn in real terms today. In 2019-20, the government spent GBP657m – a real-terms drop of more than 47%, they say.

The government said it had prioritised sport and physical activity during the pandemic and provided GBP1bn to “ensure the survival of grassroots, elite and leisure sectors”.