The Vulnerable 20 (V20) group of finance ministers, born out of the Climate Vulnerable Forum, said it had opened a dialogue with the world's largest economies in the G20.
It stressed their members' need to remove subsidies for fossil fuels to help reach the 2015 Paris Climate Agreement to keep global warming below 2C.
In its communique following a meeting in Washington DC, the V20 said:
"We call for market distorting fossil fuel production subsidies to be removed immediately and no later than 2020, and urge the G20 to set such as adopt a clear timeframe for fossil fuel subsidy elimination.
"Fossil fuel consumption subsidies need to be checked rigorously whether they provide an actual benefit to the poor, and subsequently should be replaced worldwide without harm to those relying on them for their basic energy needs.
"We urge the G20 countries to deliver their long-term low-emissions development strategies before 2020, and call on them to deliver ambitious climate change action as part of the G20 outcome in July.
"Pulling resources from climate protection will create economic instability. Investing in climate action is necessary and critical to inclusive development and economic growth."
Ambassador of Costa Rica to the US, Roman Macaya Hayes, said: "For vulnerable countries, the 1.5C limit is a matter of survival. It requires immediate and swift action by the global community, and above all, the major industrial powers."
The V20 consists of: Afghanistan, Bangladesh, Barbados, Bhutan, Burkina Faso, Cambodia, Colombia, Comoros, Costa Rica, Democratic Republic of the Congo, Dominican Republic, Ethiopia, Fiji, The Gambia, Ghana, Grenada, Guatemala, Haiti, Honduras, Kenya, Kiribati, Lebanon, Madagascar, Malawi, Maldives, Marshall Islands, Mongolia, Morocco, Nepal, Niger, Palau, Palestine, Papua New Guinea, Philippines, Rwanda, Saint Lucia, Samoa, Senegal, South Sudan, Sri Lanka, Sudan, Tanzania, Timor-Leste, Tunisia, Tuvalu, Vanuatu, Vietnam and Yemen.