The National Lottery has revealed that it pulled its funding for Heartlands, the mining world heritage centre in mid Cornwall, as the attraction had become “unsustainable” and it has a responsibility to ensure public money is well spent.

The Heartlands Trust – the charity which runs what is deemed as one of the most important mining sites in the country – and the landowner Cornwall Council issued a joint statement on Friday stating that Heartlands in Pool was unable to continue to cover its operating costs and facilities at the site will close this month.

Among the facilities to shut their doors are the Red River Café, Wheal Play soft play centre, meeting rooms and a conference centre, which proved a popular wedding venue.

The National Lottery Community Fund, which provided the biggest financial contribution towards the running of Heartlands, has revealed that it agreed with Cornwall Council not to release any further funds when it became apparent that the attraction had been unable to cover its operating costs for some time and had become unsustainable.

The National Lottery has made a financial contribution towards the maintenance of the site. The council will ensure the free adventure playground park – the largest of its kind in Cornwall – and the gardens remain open to the public. The Register Office and commercially let shops and offices will also remain open.

A spokesperson at the National Lottery Community Fund said: “Sadly, we have been informed that Heartlands has been unable to cover its operating costs for some time and has become unsustainable. We have a small endowment in place with Cornwall Council to support with maintenance at Heartlands and we have agreed with the council not to release any further funds.

“We are disappointed as we always want projects we have funded to be sustainable and successful for the community. However, we have a responsibility to ensure public money is well spent, which is why we have had to make this difficult decision.”

The Heartlands Trust says on its website that it will cease trading at the end of January and “would like to express our gratitude to everyone for their support over the past 12 years”.

There are just two more events to take place at the attraction before it closes – Cornwall Running Show on January 14 and the Healing Light Festival on January 27 and 28, which celebrates all things mind, body and spirit.

Last week’s closing statement said: “Despite the hard work and dedication over many years of the Heartlands Trust, the registered charity that runs Heartlands in Pool, and the staff there, it has become clear that Heartlands is unable to continue to cover its operating costs and facilities at the site will have to close.

“Despite its popularity, recent economic conditions have meant that utility costs have considerably increased and income from operations has decreased. All of the funding options currently available have now been exhausted and Cornwall Council is not in a position to be able to step in and provide ongoing financial support for the current operation.

“The Trust is keen that the site can continue to serve the local community; an objective that is shared with Cornwall Council, which owns the Heartlands site and leases it to the Trust. The Trust are proud of all that has been achieved at Heartlands in making it the much-loved and popular free community facility that it is today.

“Heartlands was a major project funded by the National Lottery and intended to improve life and opportunity for the local community by providing access to playground, green space, leisure, educational, heritage and community group meeting facilities. It was also seen as a catalyst for encouraging better standards of new housing development in the vicinity, rather than industrial warehousing.

“In the 12 years since it has opened, the Heartlands Trust has been extremely successful in achieving all of those objectives. Recent market research revealed that a considerable proportion of local families use both the indoor and outdoor spaces – 360,000 visitors annually use Heartlands. Well over 10,000 attend annual Bonfire Night, over 2,000 attend the annual Christmas markets and the Geekfest three-day event attracts over 8,000.

“Heartlands hosts the largest free playground in Cornwall. Local primary schools have used Heartlands as an educational resource, for children to learn about social history and their local heritage. There is a popular children’s nursery on site. Surrounding new housing developments have been quality designed and a local gardening group uses space to create a community allotment. The emerging Local Plan recognises the central role that Heartlands plays in binding the local community together.

“Throughout its life, the priority at Heartlands has always been the community. Heartlands had never seen itself as a commercial operation, but finance has always been precarious. Budget over-runs on the original build project meant vital units intended to provide rental streams were never built, and intended developer contributions for playground maintenance were never received.

“While deeply upsetting for the Trust and its staff, we all remain fully committed to the interests of our community and to a transparent approach to keeping you all informed. We will offer our full support to all the staff involved.”