A joint letter signed by Finance Watch and 19 other organisations has called on the European Insurance and Occupational Pensions Authority (EIOPA) to include climate-related transition risks for insurers' solvency capital requirements.
The organisations argued that the inclusion of transition risks would protect policyholders and taxpayers.
The letter comes ahead of a vote by EIOPA's board of supervisors on the final report concerning the prudential treatment of sustainability risks.
It noted: "As policyholders and taxpayers, European citizens expect insurance companies to protect them from current and future risks including climate change, and they trust you as supervisors to guarantee safety and soundness of the undertakings you supervise.
"This trust is maintained by ensuring that your work and that the regulatory framework you implement is based on solid empirical findings and a rigorous assessment of current and emerging risks."
Other signatories include ShareAction, Reclaim Finance, the European Federation of Ethical and Alternative Banks and Financers, and the World Wide Fund for Nature.