Insurers with $1.2 trillion under management called on Tuesday for the Group of 20 to set a timetable to phase out subsidies for fossil fuels by 2020 when they meet at a summit in China this weekend.

Aviva, Aegon NV and MS Amlin said fossil fuel subsidies were at odds with commitments by G20 nations to combat global warming agreed by almost 200 countries last year at a Paris summit.

"Climate change in particular represents the mother of all risks," Aviva CEO Mark Wilson said in a statement.

The companies called on the G20 leaders, who meet in the Chinese city of Hangzhou on Sept. 4-5, to set "a clear timeline for the full and equitable phase-out by all G20 members of all fossil fuel subsidies by 2020".

A phase-out should start with the elimination of all subsidies for fossil fuel exploration and coal production, they said. Their statement was also signed by the Institute and Faculty of Actuaries and UK-based energy firm Open Energi.

G20 leaders have repeatedly promised to phase out fossil fuels, the main man-made source of greenhouse gases blamed for climate change, since a meeting in 2009 in Pittsburgh.

The British-based Overseas Development Institute think-tank estimated that average annual subsidies for fossil fuel production were $444 billion in 2013 and 2014, roughly four times the subsidies for renewable energy in 2013.

Last week, investors managing more than $13 trillion of assets urged the G20 to ratify the Paris climate deal by the end of 2016 to help avert droughts, floods, mudslides and rising sea levels.

No G20 nations have yet completed the ratification process, according to a U.N. tracker. China and the United States, the top two emitters, are widely expected to join up around the time of the G20 summit. – Reuters