US President Donald Trump has been criticised by world leaders for his stance on climate change, ahead of the global COP30 summit.

President Trump, who is not attending the meeting in the Amazonian city of Belém, was called a liar by the leaders of Colombia and Chile for his rejection of climate science.

UK Prime Minister Sir Keir Starmer acknowledged the waning political support on climate change. He said it had been a unity issue internationally and in the UK but 'today sadly that consensus is gone.'

Over the next two weeks, countries will try and negotiate a new deal on climate change, focusing especially on channelling more money to forest protection.

Many leaders from the world's largest nations – India, Russia, US and China - are notably absent from this year's summit.

And while Trump isn't attending this meeting in Belém, his views on climate change are certainly on the minds of many of the other leaders present.

Speaking at the UN in September, the US president said that climate change was 'the greatest con job ever perpetrated on the world'.

Without naming the US leader, President Luiz Inácio Lula da Silva of Brazil warned on Thursday of 'extremist forces that fabricate fake news and are condemning future generations to life on a planet altered forever by global warming'.

The leaders of Chile and Colombia went further, calling the US president a liar, and asking other countries to ignore US efforts to move away from climate action.

Maisa Rojas, Chile's environment minister, told the BBC: 'The science is very clear. It is very important not to falsify the truth.'

While Trump-bashing went down well with the audience, getting agreement on new steps to tackle warming is proving much harder.

Only a few dozen leaders have turned up in Belém, and a majority of countries have failed to submit new plans to cut carbon emissions, the root cause of rising temperatures.

Despite Starmer acknowledging that global political support for the climate movement is waning, he told the gathering: 'My message is that the UK is all-in.'

However, on Wednesday night, in a blow to the Brazilian hosts, the UK chose to opt out of its flagship $125bn fund to support the world's rainforests.

The protection of these ecosystems is crucial for tackling climate change - they cover just 6% of the world's land, yet store billions of tonnes of planet-warming gases and host half of the planet's species.

The move by the UK has come as a surprise as it had been heavily involved in the fund's design and launched a global commitment for countries to halt deforestation by 2030 when it hosted the COP summit in Glasgow in 2021.

Lord Zach Goldsmith, who worked on the issue when he was environment minister, told the BBC's PM programme: 'The assumption was that the UK would be a leading participant, and at the last minute the UK has walked away. It has caused real frustration, to put it mildly, here in Brazil... the Brazilian government behind the scenes is furious.'

Prince William tried to encourage leaders to overcome their differences and move forward with action, urging them to take action for the sake of their children and grandchildren.

From Monday, countries will spend two weeks negotiating further action on climate change, focusing on questions regarding how to raise finance previously pledged for those already affected by the worst impacts of climate change. The last few weeks have seen devastating extreme weather globally, including Hurricane Melissa, which resulted in over 75 deaths.