Climate and anti-poverty activists have launched a 24-hour "Twitter storm" against the hundreds of billions of dollars of government subsidies paid each year to the petroleum and coal industry, despite the global economic downturn and the rise in emissions.

The blitz, which has been supported by Stephen Fry, Robert Redford, actor Mark Ruffalo, politicians and environmentalists, took the hash tag #endfossilfuelsubsidies up to number two in the ranking of globally trending topics and number one in the US.

"We're averaging a tweet a second, but it picks up when celebs hit the hashtag," said Jamie Henn of www.350.org, a climate group that is among the leaders of the campaign.