Instead, Western governments and businessmen should pool their efforts in the search for non-traditional sources of energy and make more effort to use energy efficiently, he said.

Mr Gorbachev, the founder of the Geneva-based environmental group Green Cross International, recalled his own bitter experience of the dangers of nuclear energy. “With my experience of Chernobyl, I know what I am talking about,” he said, referring to the catastrophic nuclear plant explosion near Kiev in 1986. The Soviet Union had been forced to spend tens of billions of roubles to combat the radiation danger, he said, but the pollution of the soil, earth and air was still causing long-term damage.

Addressing Britain’s all-party parliamentary group on climate change, Mr Gorbachev also spoke of the urgent need to combat climate change and global warming, which he said could expose some 400 million people to famine and death because of water shortages.

His call follows hard on the heels of an appeal to Tony Blair by 14 prominent British businessmen to give a clearer lead on climate change. Mr Gorbachev wrote last month to Mr Blair and other leaders of the G8 group of economies, urging them to seize the opportunity at the St Petersburg summit to make strong commitments to “a truly secure and sustainable energy future”. He therefore welcomes the creation of the Climate Change Dialogue between parliamentarians and business leaders.

He also told Mr Blair that Green Cross was “concerned” over statements made at a recent meeting of G8 energy ministers on security for the supply routes of oil and gas and facilitating growth in nuclear power. Such an approach “lacks vision”, he told the Prime Minister, and, by relegating renewable energy and energy efficiency to secondary status in the talks, showed that the G8 was failing to move forward on the real solutions to the energy and climate change crises.

Mr Gorbachev, who at 75 still travels the world to campaign for the environment, admitted that many governments now saw nuclear energy as the “lesser of two evils” in the fight to reduce carbon emissions. But this was missing the point. By the end of this century coal would be the only fossil fuel left on the earth. It was essential to start the search now for non-traditional supplies. And he predicted an acute energy crisis within 20 years.

He told MPs that it was always easy to find $80 billion to finance an invasion, but Green Cross was calling for a $50 billion fund over the next ten years to seek new energy sources.

He painted a bleak picture of a global deficit in water. Some 1.2 billion people did not have access to safe drinking water and 2.4 billion had no proper sanitation. Every day 6,000 children died because of a lack of safe drinking water, and over the past decade diarrhoea had killed more than all the wars since the Second World War.

“Water wars” could break out in the basins of the world’s great rivers such as the Ganges and the Mekong. If shortages were not addressed, a third of the world’s population would be without water by 2020 — “and 2020 is just tomorrow”, he said.

Times Recommends

• 'Great Schlep' may seal deal for Obama
• Hindu 'storm troopers' flex their muscles
• Ahtisaari: deserved reward for (failed) plan