HARTFORD, Conn. – A major insurer is limiting its coverage of companies in the fossil fuel business, citing concerns about climate change.

The Hartford Financial Services Group Inc. won’t cover companies that get more than a quarter of their revenue from thermal coal mining or that produce more than a quarter of their energy from coal.

The company also said it will not write policies or make investments in companies that generate more than 25% of their revenue directly from extracting oil from tar sands. It won’t cover or invest in the construction and operation of new coal-fired plants.

The company said it plans to phase out policies or investments that currently violate those parameters by 2023.

The Hartford posted around $19 billion in revenue in 2018. The company joins 18 global insurers in limiting or dropping coverage of energy companies that tend to rely on fossil fuels, but the Rainforest Action Network said The Hartford is the “first mainstream U.S. insurer” to restrict coverage for tar sands oil and coal.

The company is aiming to balance the need for energy and economic growth with concerns about a warming planet and the role of fossil fuels, CEO Christopher Swift said.

“The world needs affordable, accessible energy to support global economic progress and at the same time action is needed to mitigate the impact such activity has on our climate,” he said.