RIO DE JANEIRO -- U.K. Deputy Prime Minister Nick Clegg today pledged to make all companies listed on the London Stock Exchange start counting greenhouse gas emissions during an address here.

Clegg, speaking at the Rio+20 sustainable development summit, said all companies listed on the world's fourth largest exchange will have to disclose their carbon emissions starting next year or trade elsewhere.

The announcement makes the United Kingdom the first to require greenhouse gas accounting from corporations, Clegg said.

"We will be the first country anywhere that is obliging those companies ... to report about their own activities," he said.

Clegg's remarks came during a side event here on natural capital accounting that was interrupted by a protester who said the British government was intent on "selling off the world's resources" and taking advantage of indigenous groups. The protester was quickly swept out of the packed room.

In response, Clegg addressed criticism prevalent here that the U.N. conference is low on ambition and likely to produce only a watered-down declaration (ClimateWire, June 20). Clegg said the Rio conference will push "all of us towards a world in which we treasure, measure and protect sustainable development in a way that we have never done before."

"Any text that is agreed to by 190 countries from different hemispheres will always involve compromises, will always involve diluted phrases," he said.

Click here to read the 49-page text that is likely to become the official Rio Declaration by week's end.