THE failure of successive Governments to get children to be more active is mass "child neglect", experts have warned.

Despite a weight of evidence showing the benefits of regular exercise, all political parties have " neglected state policy on child physical activity for decades", according to an article in a leading medical journal.

The authors, including West Ham football manager Sam Allardyce, said that this is "tantamount to state child neglect".

Writing in the British Journal of Sports Medicine, the authors said that leadership and strategy on the issue are "totally absent".

Regular exercise in childhood can help boost academic performance, curb antisocial behaviour, improve general health and wellbeing, the experts from University College London Hospitals NHS Foundation Trust, Liverpool John Moores University and the Sydney School of Public Health said.

But despite this only 33% of boys and 21% of girls aged four to 15 meet the minimum levels of physical activity for basic health benefits, they said. And school children spend an average of seven to eight hours a day being sedentary.

They wrote: " All political parties have neglected state policy on child physical activity for decades. While physical activity guidelines recommend children to spend at least an hour a day being physically active, schools are able to provide no physical education, optional physical education or limited physical education opportunities.

"Furthermore, a lack of focus, political and public debate on these issues highlights a lack of interest of political parties and education authorities in the physical literacy of our children and future citizens.

"Given the overwhelming evidence supporting physical activity for the physical health, mental health and productivity of children, the lack of policy, lack of cross party debate and interest, lack of leadership and strategic action on physical activity within schools are complicit and tantamount to state child neglect."

The amount of time children spend in physical education and activity while at school is neither monitored nor known by any educational or regulatory authorities, they said. And there is no statutory minimum requirement for schools to devote a specific amount of time to PE.

The authors also said that h ealth and sporting legacies associated with the London 2012 Olympics are fast becoming a "distant memory".

At the same time of the Games, where Team GB came third in the medals table, women and men from Britain came first and second, respectively, in the European obesity league tables, they said.

Following the Olympics, ministers announced they would plough £300 million into primary school physical education over two years, but the authors said that the figure was a "derisory gesture".

"It is nearly one year following the 2012 London Olympics, with political and Olympic bid promises of youth health and sporting legacies turning rapidly into a distant memory," they wrote.

The authors concluded: "The minimal funding, lack of interest and absence of a child physical activity strategy strongly support the notion that the state is failing to act to prevent harm against children and failing to meet children's basic physical needs likely to result in the serious impairment of their health and development.

"This is quite literally indistinguishable from the government's own definition of child neglect."

A Government spokesman said: "This Government is taking decisive action to harness the Olympic spirit and make sure every child has the opportunity to be fit and healthy.

"We have extended our ringfenced funding for primary schools to spend on sport to 2015/16 - with a total of £450m now going directly to headteachers to improve PE and sport in their schools.

"In addition we have spent £3 million to extend Change4Life sports clubs to schools in areas with the highest childhood obesity, we are targeting funding to get more 11 to 25-year-olds playing sport, and we are investing in facilities to strengthen grassroots sport up and down the country."