"There are credibility issues and there are cowboys around," said Jonathan Shopley, chief executive of the CarbonNeutral Company. "It is probably to be expected for an industry at this stage, but we need a set of standards and outside verification so that self-regulation can engender trust and integrity in the market."

CarbonNeutral is one of the largest offsetting companies in the United Kingdom, and the Guardian said its rapid growth highlights the attention being paid to climate change and offsets.

Shopley's comments were reported by the Guardian newspaper Monday and come as some of the world's largest companies are eschewing offsets because of the ambiguous nature of some of the schemes being adopted to offset emissions.

Under carbon offsets, an entity pays to reduce emissions elsewhere in order to counter its own greenhouse gas emissions. This can take the form of setting up environmentally friendly programs elsewhere. The problem in many cases is that some of these programs are set up in developing nations where it is difficult to ensure the quality of the project.

Details of a standard would be ready by July and launched in September, said Mark Kember, policy director of the Climate Group. The newspaper said his group had worked with the World Economic Forum and other groups on the standards.

"There is a lot of confusion out there with people buying offsets without having the certainty that it will result in emission reduction," said Kember said, according to the paper.