Almost 200 million tons of CO2 greenhouse gas -? equivalent to around a third of the UK’s currently declared annual emissions -? is missing from the annual reports of major companies operating on the London Stock Exchange, according to a report (PDF) from UK-based Christian Aid. The charity wants voluntary guidelines on how to report emissions made mandatory.

The UK’s Department for Environment, Food and Rural Affairs responded by criticizing the methodology of the Christian Aid research. “Under internationally agreed guidelines, carbon dioxide emissions associated with the production of goods are reported in the greenhouse gas inventory of the country in which the goods are produced,” a spokesperson said, according to IntheNews.

Christian Aid has launched a campaign against Barclays Bank and Morrison’s Supermarket demanding they publish the true extent of their carbon emissions and then commit to a five percent annual reduction.

Christian Aid says that only 16 out of the 100 companies on the FTSE 100 Index properly report their basic emissions according to established standards. If all members of the FTSE 100 applied these standards to their emissions reports, it is estimated that these companies would have to declare a further 190.65 million tons of carbon.

“For the UK also to report these emissions would be double-counting,” The UK government spokesman said. “There is therefore no transfer of emissions to the UK when goods are imported. Similarly, the UK is responsible for, and reports in its greenhouse gas emissions inventory, emissions of carbon dioxide associated with the production [of] goods that are subsequently exported by the UK.”