Rio+20 to push sustainability reporting Thousands of companies worldwide will be pushed to report on their environmental strategies and performance under proposals to be finalised at a UN summit in Rio de Janeiro this week. The move is being resisted by some countries, including the US, Canada and India, according to people close to the negotiations, because of fears that it will add to companies" regulatory burdens. But it is being backed by many European countries, including the UK, which has included a leading campaigner for the measure, Aviva the insurer, in its official delegation. A final decision will be made at the end of this week by more than 100 world leaders at the Rio+20 UN conference on sustainable development, which the UN says is the biggest event it has held. Called Rio+20 because it comes 20 years after the 1992 UN earth summit in the same Brazilian city, Rio+20 has been targeted by a group of businesses and investors, such as Aviva, that say both companies and investors benefit from long-term consideration of forecast squeezes on energy, water and other resources. Their campaign has led to the inclusion of a section in the summit text that leaders are to agree by Friday that says governments should develop a "model for best practice and facilitate action" for so-called corporate sustainability reporting. One of the models cited by campaigners as an example others should follow is Denmark's "report or explain" requirement for large companies either to produce a report on their behaviour or explain why they have not. "It shouldn't be inordinately expensive in terms of time and money to produce this reporting," said Paul Abberley, chief executive of Aviva Investors, adding: "I think a lot of the objections we pick up are based on fears that aren't really grounded." About 95 per cent of the 250 largest global companies now report on their corporate responsibility activities, a jump of more than 14 per cent from 2008, according to a KPMG survey. But two-thirds of those who do not report are based in the US, the world's biggest economy, and the picture is more mixed among smaller businesses. Caroline Spelman, the environment secretary, told the Financial Times that although her government was backing the "report or explain" model, it did not want to add more regulatory burdens to companies. "What we want to do as a first step is promote British companies that are doing this," she said. Separately, the UN is backing a measure for stock exchanges to push companies listing with them to do more reporting on their sustainability strategies. This is not included in the Rio+20 text that leaders will negotiate, but backers of the move hope that some exchanges might announce steps to encourage such reporting this week in Rio.