New sports facilities in London are being built too slowly to cater for an increase in demand as part of legacy plans for the London 2012 Olympics, according to a report by Drivers Jonas.

The consultancy firm has raised concerns that government pledges to use the London Games to promote healthier lifestyles could be undermined, after the second Sports Crane Survey found that the number of sports centres opened or refurbished across London during the last two years had slowed mainly due to the recession. Researchers found that a total of 61 of London's sports facilities were either opened or refurbished between 2007-08 - the same number reported in the first Sports Crane Survey for the 18-month period between the decision to award the Olympics to London in July 2005 and the end of 2006.

However, the number of planned construction schemes has been reduced from 36 to 21, while the London Boroughs of Brent; Kensington and Chelsea; Merton; Newham and Redbridge all reported no new openings during the past two years. A spokesperson for Drivers Jonas said: "The dramatic change in the economic environment since London won the Olympics means that delivering sufficient new facilities to cater for the projected increase will be equally testing.

"Flexible spaces - dance studios, sports halls and all-weather pitches - will play an important part in matching the changing interests of the public. The government will have to rely more on innovative policies than boosts to supply to encourage those who don't exercise to start getting fit." Concerns were echoed by Tim Lamb, chief executive of the Central Council for Physical Recreation (CCPR), who said that London faced the prospect of missing out on a "spectacular opportunity" to capitalise on the impact of the 2012 Games if sports facilities were not provided on time.

Lamb said: "We need sporting facilities to be built now, so that they are ready to welcome the thousands we hope will be inspired by the sports they have been watching. "The 2012 Olympics are our chance to make London and the rest of the country a healthier and more active city, and it would be tragic to see that wasted."

Sport England believes that, while continued investment in the development of new sports facilities is crucial in the run-up to the London 2012 Olympics, the success of the government's pledge to increase participation also relies on the standard of coaching that is available. A spokesperson for Sport England said: "We are bringing together local councils and sports governing bodies to ensure that existing facilities are maximised and opportunities are created for people to develop lifelong sporting habits as part of the 2012 Olympic and Paralympic Games participation legacy.

"We must however remember that beyond facilities alone, increasing sports participation will depend upon fostering the enthusiasm, motivation and efforts of all those involved in sport in the capital, from volunteers and coaches to schools, clubs and local authorities."