Insurers are withdrawing cover for thermal coal as regulation and ethical practices have a growing impact on the industry.

A market update from Aon warns thermal coal miners to check their policies and relationships with their insurers, because some companies are ceasing to offer property and construction insurance.

Rates for thermal coal risk may face pressure from 2020 as market capacity drops, Aon says.

Meanwhile, the update notes higher natural catastrophe claims have put upward pressure on rates and premiums. More detailed and technical underwriting is needed, and renewal processes are taking longer, Aon says.