Grassroots sports participation is plunging creating a couch-potato culture of obese children, councils are warning.

The number of people aged 16 and above taking part in sport at least once a week has dropped by 400,000 since the 2012 Olympics. This is down from 15,890,400 people in 2011-12 to 15,491,200 in 2014-15.

New figures also show worrying levels of obesity in the UK. More than 135 people with diabetes have a leg, foot or toe amputated each week and four out of five of these amputations are preventable. It is estimated that obesity costs the NHS £4.2bn a year and physical inactivity about £1.1bn.

Councils warn that a ‘lost generation’ of obese and physically inactive teenagers is the result of the decline in participation in sports.

Currently, nearly half a billion pounds is awarded by Sport England, the governing body, to national sports bodies to increase participation. Out of the 46 sports only six (athletics, cycling, netball, table tennis, archery and fencing) have so far shown a significant rise in participation rates.

In a new submission to the Government, which is drawing up a new sports strategy, the Local Government Association (LGA), argues that national funding should be devolved through Sport England to councils and local partners in a bid to boost active lifestyles and in turn reduce obesity and ease pressure on the NHS.

Cllr Ian Stephens, chairman of the LGA's Culture, Tourism and Sport Board said: ‘Councils are best-placed to reach those who play sport or want to start doing so, as most sport takes place in swimming pools, leisure centres, parks and open spaces owned or managed by local authorities. However, they are being hamstrung by a national funding system which is not fit for purpose.’

He continued: ‘Councils need the opportunity to spend this sports funding in the most effective way - on the parks, playing fields and facilities where it can best reach the most people to get active and feel healthier.’