The pontiff, speaking at St. Peter's Basilica, asked God to enlighten "those who hold power and money so that they avoid the sin of indifference... and take care of the world we inhabit."

His comments came in the first celebration of "World Day for Prayer for the Care of Creation," which the pontiff created to boost support for the environment.

Francis has become a leading defender of green causes, particularly in the fight against climate change, and is due to address the UN Special Summit on Sustainable Development this month in New York.

UN members will gather in Paris from November 30 to December 11 in a bid for a deal to cap heat-trapping carbon emissions, the driver of man-made climate change.

The goal is to limit the temperature rise by by two degrees Celsius (3.6 degrees Fahrenheit) over pre-industrial levels, but the negotiations have proved long and hard.

A crunch round of talks opened in the western German city of Bonn Monday, with delegates facing a sprawing 83-page draft of sometimes contradictory proposals.

On Monday, US President Barack Obama described climate change as an "urgent and growing" challenge that would define this century.

"Human activity is disrupting the climate, in many ways faster than we thought," he said.

"The deniers are increasingly alone, on their own shrinking island.

"The science is stark, it is sharpening, and it proves that this once-distant threat is now very much in the present." - AFP