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* World's biggest 800 firms ranked on emissions transparency
* Only 37 pct publicly disclose complete emissions data
By Nina Chestney
LONDON, May 1 (Reuters) - Most of the world's largestcompanies do not report their greenhouse gas emissions fully orcorrectly and do not have the data independently verified, astudy by an environmental research body showed on Wednesday.
Companies are under pressure worldwide from policymakers,and a public increasingly concerned with green issues, to reportthe environmental fallout of all activities related to theirdaily business - from plane journeys to office supplies.
Officials hope the data generated can point to potentialenergy savings and encourage firms to reduce their emissions,while many companies see it as a way of planning for exposure tolong-term costs such as taxes on emissions.
But for now London is the only stock exchange that forcesall major companies to report in detail andmany, particularly in emerging markets like Russia and acrossSoutheast Asia, have all but ignored the idea.
The Environmental Investment Organisation (EIO) found thatjust 37 percent of the world's 800 largest companies companiesdisclosed complete data and correctly adopted the basicprinciples of emissions reporting.
Only 21 percent had their data externally verified and onlyone firm, German chemicals producer BASF, reportedemissions across its entire value chain - from sources such asbusiness travel, transport, distribution and investments. Thistransparency placed it at number one in the rankings.
"This ought to be a wakeup call for companies. Since themajority of total corporate emissions often come from (valuechain) sources, large quantities of emissions are not beingaccounted for," said Sam Gill, chief executive of the EIO.
"Not only could this be a source of unmeasured risk forcompanies but it also means we are not getting the full picturein terms of corporate emissions," he added.
Companies are increasingly measuring and disclosing theirenvironmental performance in their annual reports. However, thelack of a universally accepted or mandatory standard means bothreporting formats and content vary widely.
The rest of the best 10 companies at reporting emissionswere telecoms firms such as Canada's BCE, SingaporeTelecom, Spain's Telefonica, BT Group and Deutsche Telekom, according to the EIO.
The bottom 10, with no publicly disclosed emissions data,was made up of mainly Russian and U.S. utilities and oil and gascompanies, such as Phillips 66, Lukoil, EdisonInternational and First Energy.
The EIO based its findings on the latest publicly availabledata, which for most companies was from 2011.
