Some coal producers are having to set aside tens of millions of dollars to cover their own risks as they are cut adrift by insurers, making it more difficult and costly to do business amid a surge in demand for the fossil fuel.

Dozens of insurers have announced restrictions on their cover for the coal industry, particularly for new projects, in response to pressure from shareholders, governments and environmental groups who want to limit coal's contribution to global warming. This follows similar moves by banks to restrict their coal financing activities.

Coal miners need extensive insurance, including for operations, property, equipment and environmental liability. Three insurance brokers said it can now take months and dozens of inquiries to find such coverage for a coal client.