Countries are being urged to commit hundreds of billions of pounds in funding to protect nature in a global campaign backed by Sir David Attenborough.

Conservation organisation Fauna and Flora International (FFI) is launching the Our One Home campaign, calling on governments and businesses to prioritise protection and restoration of nature and wildlife.

To mark the launch, FFI has co-ordinated a letter signed by more than 110 nature conservation groups from more than 40 countries, to the UN secretary-general, calling on countries to commit an initial 500 billion US dollars (£390 billion) to conserving nature and preventing a wave of extinctions.

The campaign has been backed by Sir David, along with celebrities including Dame Judi Dench, Stephen Fry, Hugh Fearnley-Whittingstall, Giles Clark and James Wong.

Sir David, vice-president of FFI, said: “Our natural world is under greater pressure now than at any time in human history, and the future of the entire planet – on which every single one of us depends – is in grave jeopardy.

“We still have an opportunity to reverse catastrophic biodiversity loss, but time is running out.

“We urgently need world leaders and global businesses to acknowledge the crucial importance of nature, commit to investing in it, and unite behind a massive collective effort to conserve it.”

Dame Judi said: “Across the world, many species and natural resources are under threat from the devastating effects of climate change and we cannot afford to be complacent.

“As a vice-president of FFI, I am proud to endorse this much-needed campaign which seeks to bring funding to local conservation organisations who are best-placed to deliver long-lasting change for our natural world.”

The campaign comes as the UN hosts a biodiversity summit aimed at reversing the crisis facing nature, with a million species at risk of extinction and wildlife populations falling by more than two thirds on average since 1970.

The UN recently warned the world failed to meet any of a series of goals agreed a decade ago to halt and reverse declines in biodiversity – the plants, animals and other organisms on Earth – by the deadline of 2020.

The World Economic Forum estimates the natural world is worth 125 trillion US dollars (£97 trillion) to the economy, but FFI said that instead of being valued and protected, it was being destroyed.

FFI’s Our One Home campaign calls for a 500 billion US dollar yearly funding commitment, led by governments and including private sector organisations, and scaling up by 50 billion US dollars a year (£39 billion), to help local conservation organisations restore and protect nature.

The letter led by FFI says the scale of funding is “critical” for future nature restoration and for more immediate Covid-19-related relief, where cutbacks to frontline staff have opened the door to environmentally damaging activities.

And more funding must find its way to grassroots level and local communities where it will be used most effectively.

The letter also calls for changes to finance flows, including an increase in overseas aid spending for conservation and a reduction in fossil fuel subsidies to help nature.

Mark Rose, chief executive of Fauna and Flora International, said: “The natural world is crucial to human and economic health, but is under immense pressure and remains drastically underfunded.

“UN member states must take the lead in getting ahead of this crisis and putting funding into the hands of those who are best placed to use it – local conservation organisations who see first-hand the challenges facing the natural world and have the knowledge necessary to secure real change.

FFI is urging the general public to support its campaign by signing a public petition on Change.org at: https://www.change.org/OurOneHome