The widow of American billionaire Douglas Tompkins has begun talks with Chilean President Michelle Bachelet over the donation of a vast nature reserve in southern Chile.

Kristine McDivitt Tompkins said she had formally offered Chile 400,000 hectares of land in Patagonia to be made into national parks.

The negotiations are expected to take two years.

Douglas Tompkins, who died in December 2015 in a kayaking accident, caused controversy in the 1990s by buying up land in southern Chile and Argentina to preserve it.

Last month, Kristine McDivitt met the new Argentinean President Mauricio Macri to donate to the country 150,000 hectares of threatened wetlands near the border with Brazil, with the aim of creating the Ibera National Park.

Douglas Tompkins was a globe-trotting rock climber and skier in his youth who was the co-founder of the outdoor clothing company The North Face.

In the early 1990s Douglas Tompinks got divorced, abandoned corporate life and moved to isolated southern Chile.

With his second wife Kristine, a former CEO of outdoor clothing company Patagonia Inc, he began buying up land in order to protect an ancient forest in Patagonia.

Over 25 years Douglas and Kristine Tompkins invested more than $375 million in conservation, donating part of their lands in Chile and Argentina to create four national parks.

After the meeting with President Michelle Bachelet, Kristine McDivitt said that the donation of the latest tranche of land to Chile was being made on condition that it would be used to create national parks which people could freely visit.

“The process will take a long time,” she said.

“We won’t be deciding the timing and I know there will be a compromise both sides will have to make to work through all the stages that will be necessary.

“We want people from all over the world to be able to visit these places. With the donation of these parks, Chile will be able offer a historic legacy to the world.”

In 2005, Douglas and Kristine Tompkins donated another tranche of land to Chile, 294 hectares near the Corcovado volcano, creating the sixth largest national park in Chile – the Corcovado National Park.