Britain's Prince Charles has slammed climate change sceptics.

The 64-year-old royal insists the risk of not doing anything about protecting the rainforests is "too great" and he urged world leaders to "act now" or risk the Earth becoming a "dying patient".

Speaking in a speech to ministers and tropical forest scientists at St James's Palace in Central London, he said: "If you think about the impact of climate change, [it should be how] a doctor would deal with the problem.

"A scientific hypothesis is tested to absolute destruction, but medicine can't wait. If a doctor sees a child with a fever, he can't wait for [endless] tests. He has to act on what is there.

"The risk of delay is so enormous that we can't wait until we are absolutely sure the patient is dying."

The Prince of Wales also hit out at businesses who are failing to protect the environment.

Charles - whose eldest son Prince William is expecting his first child with wife Duchess Catherine - recently said the prospect of becoming a grandfather has reinforced his desire to help save the planet.

He explained: "I've gone on for years about the importance of thinking about the long-term in relation to the environmental damage, climate change and everything else.

"We don't, in a sensible world, want to hand on an increasingly dysfunctional world to our grandchildren, to leave them with the real problem.

"I don't want to be confronted by my future grandchild and [have] them say, 'Why didn't you do something?' So clearly now that we will have a grandchild, it makes it even more obvious to try and make sure we leave them something that isn't a total poisoned chalice."