Pressure is mounting on investors to pull the billions of pounds they pour into fossil fuel firms because of dangers to human health and the environment.

In a new report, doctors are calling for investments in coal, oil and gas companies to be withdrawn. They blame the industry for air pollution that is killing over 2,000 people a year in Scotland.

According to campaigners, over 180 institutions around the world, including city councils, universities and churches, have committed to ending £30 billion of fossil fuel investments. Protests are planned this week in Scotland and other countries to help persuade more investors to join them.

Last week the Norwegian government's £556 billion pension fund disclosed that it had withdrawn investments from 114 coal, tar sands and other companies because of environmental concerns. Founded on revenues from North Sea oil and gas, it is the largest sovereign wealth fund in the world.

Last October the University of Glasgow decided to immediately freeze and then phase out fossil fuel investments over the next 10 years. The university's governing court is due to receive a report on the financial impact of its move at a meeting later this month.

"Fossil fuels can no longer be considered an ethical investment," said Martin McKee, Professor of European Public Health at the London School of Hygiene and Tropical Medicine. "This is one of the defining challenges of our time."

The new report, entitled 'Unhealthy Investments', has been backed by five medical campaign groups. The medical profession led the call to disinvest in tobacco companies 20 years ago, it says, and should now insist that money is taken away from polluters.

"The link between fossil fuels, air pollution and climate change are clear, and the health impacts are unacceptably high," said Dr David McCoy, director of health charity Medact, one of the groups behind the report.

"This report sends an unequivocal message that the health sector should end its financial association with the fossil fuel industry. We need a radically different and more sustainable pattern of energy production and consumption."

He was supported by Edinburgh GP, Dr Lesley Morrison, who said that over 2,000 premature deaths a year in Scotland were due to air pollution caused mainly by fossil fuels. "It is unacceptable that, in the 21st century, air pollution is responsible for the deaths of so many people," she said.

A major scientific study last month concluded that 80 per cent of the world's coal, 50 per cent of its gas and 33 per cent of its oil would have to stay in the ground to avoid catastrophic climate change. Leading financiers, including the president of the World Bank, Jim Yong Kim, have highlighted the risks of fossil fuel investment.

A recent report for the umbrella group, Scottish Environment Link, warned of a "carbon bubble" that could burst and trigger a major economic crisis. It called on Scotland to show leadership in managing the exit from fossil fuels.

"By investing in coal, oil and gas we are gambling away a healthy planet," said Ric Lander, finance campaigner with Friends of the Earth Scotland. "People across Scotland are beginning to ask those looking after their money why it's being used to destroy their future."

The Sunday Herald revealed in January 2014 that five major public sector pension schemes in Scotland were investing £1.11 billion in fossil fuel companies, £204 million in tobacco companies and £113 million in arms dealers.

The doctors' report prompted a fierce counterblast from Malcolm Webb, the chief executive of Oil and Gas UK, which represents the offshore industry. He accused the authors of failing to recognise that gas can be used to replace coal and cut carbon emissions.

They also ignored the fact that oil and gas were needed to power the economy for the foreseeable future, he said, and didn't realise that 85 per cent of the world's fossil fuels were owned and explored by governments, not companies.

He added: "Personally speaking, I find the lack of proper understanding of the realities of energy supply which these comments, from no doubt well-meaning doctors, demonstrate, to be quite staggering, indeed very worrying."