Leonardo DiCaprio

The Hollywood star, who is a UN climate change representative, was seen at the Kew Carbon Garden exhibit on Tuesday at the main conference centre.

He was mobbed by journalists, fans and delegates as he entered the building.

The Titanic star also took part in a fringe event on Monday, posing with film producer Paul Goodenough, founder of charity Rewriting Extinction.

People who give to the All In Challenge will be entered into a prize draw.

The campaign was launched on Tuesday to help feed vulnerable people in the US and has already raised $5.6m (£4.4m).

Ellen DeGeneres, Kevin Hart, Justin Timberlake, Justin Bieber and many US sport stars have also offered donors a chance to get up close and personal.

Bieber has promised to fly to one lucky fan's house - once the lockdown is over - for a private performance of his 2009 hit One Less Lonely Girl.

He was speaking at the premiere of his documentary about environmental issues, Before The Flood, at the London Film Festival.

The film sees the Oscar-winning actor travel the world to see the impact of global warming first hand.

He says there are many things young people can do, but the most important is to use their vote.

"I think this is the issue of [young people's] generation and there has been a huge movement out there from the youth," he told Newsbeat.

Otherwise he must step down from his position as a United Nations Messenger of Peace, a role in which the actor focuses on the issue of climate change.

"Leonardo DiCaprio has consistently refused to explain his close personal and financial ties with key persons of the Malaysian 1MDB scandal," said Lukas Straumann, director of Switzerland-based rainforest charity, the Bruno Manser Fund, in a statement. "This is unacceptable."

Though the Oscar winner does have a plethora of talents, reportedly including rapping, archery is not among them. However, DiCaprio appears to have a look-alike on the U.S. Men's Archery Team by the name of Brady Ellison

Actor Leonardo DiCaprio is reportedly set to host an event for Democratic presidential nominee Hillary Clinton on August 23 in Los Angeles when she visits there.

The function's called a "Conversation with Hillary" and is priced at $33,400 per person, according to Variety.

"The first $2,700 will go to the Clinton campaign, and the remainder will go to the Democratic National Committee and state and local parties," Variety reported.

The Oscar winner recently made a one-day visit to protected Mount Leuser National Park in northern Sumatra and uploaded photos to his Instagram account, expressing concerns over species whose habitats are threatened.

"The expansion of palm oil plantations is fragmenting the forest and cutting off key elephant migration corridors," he posted.

And she should know. In 2008, she was mauled by a real life bear while out walking her dogs on her ranch in California. 

Hansen lost 14 teeth, her nose and her ears in the attack. She escaped by sticking her thumbnail into the bear's eye while her dogs scared it off with their barking. And that was a comparatively small bear. 

The image was posted to Facebook by the History in Pictures Facebook page to commemorate DiCaprio's long-awaited Oscar win. 

It shows a young Leo being held by his mother Irmelin and his father, George DiCaprio. 

The 41-year-old actress told the BBC during a recent interview: "I think you can sort of feel it, and I think that everyone wants it for him," she said.

"It would be amazing."

DiCaprio has received wide-spread critical acclaim for his role in The Revenant, in which he portrays a dedicated frontiersman Hugh Glass.