WASHINGTON (Reuters): The U.S. Export-Import Bank has mischaracterized potentially hundreds of large companies and units of multinational conglomerates as small businesses, a flaw in its record keeping that could undermine the export lender's survival strategy.

A Reuters analysis showed companies owned by billionaires like Warren Buffett and Mexico's Carlos Slim, as well by Japanese and European conglomerates, were listed as small businesses and Ex-Im acknowledged errors in its data in response to those findings.

Bank officials and supporters have used Ex-Im's support for American small business as the first line of defense against conservatives' campaign to shut it down as an exponent of "crony capitalism."

The bank just won a nine month extension of its mandate in September and faces a bruising battle over the next seven months to secure its future.

A comparison of some 6,000 businesses characterized by Ex-Im as "small" with information supplied by corporate data collector Dun & Bradstreet, which Ex-Im also uses to vet applicants, and other sources turns up some 200 companies that appear to be mislabeled and many more whose classification is uncertain.

A division of Austria's Swarovski jewelers shows up, as does North Carolina's Global Nuclear Fuels owned by General Electric (>> General Electric Company) and Japan's Toshiba (>> Toshiba Corp) and Hitachi (>> Hitachi, Ltd.).

The extent of the errors, which also mean some genuine small business transactions are not labeled as such, is not clear. Separate Ex-Im databases don't even agree with each other.

Responding to a list of 10 examples provided by Reuters, Ex-Im acknowledged errors in most of them, but argued their impact was small and that the mislabeling of small firms as large ones may have a greater bigger effect on the total tally of small business support. A spokesman said the bank aimed to be as transparent as possible.

"When it comes to our data, we strive for 100 percent accuracy, and anything less is unacceptable, which is why we are constantly improving our systems,” he said, pointing to Ex-Im's recent hiring of a chief information officer, an overhaul of databases and a review of paper documents.

In an emailed response to Reuters, the bank cited five examples in which small firms were labeled as large firms by mistake.

The errors make it difficult to identify exactly how much Ex-Im support goes to big business like Caterpillar (>> Caterpillar Inc.) and how much to small firms.

The problem is primarily political, as there are no legal implications of businesses being misclassified by Ex-Im, since it does not set money aside specifically for firms that meet industry-specific revenue and employee limits set by the Small Business Administration. The SBA guidelines exclude firms that may be small but are owned by deep-pocketed conglomerates.

SLIM AND BUFFET

Reuters calculations show that as much as $3 billion in authorizations listed as those for small business may have been misclassified over eight years - roughly 8 percent of Ex-Im's $38 billion in small business support over that period. Total authorizations were worth $189 billion.

For example, among "small business" beneficiaries is Texas-based Condumex Inc. the U.S. sales operation for Mexico's Grupo Condumex, a subsidiary of Slim's Grupo Carso (>> Grupo Carso S.A. de C.V.).

Or take Brock Grain Systems, a division of CTB International Corp., which has been owned by Buffet's Berkshire Hathaway (>> Berkshire Hathaway Inc.) since 2002.

In its battle to survive, Ex-Im has presented its statistics with exacting precision.

Ex-Im says that in the fiscal year ending Sept. 30, it engaged in 3,347 transactions supporting small businesses, accounting for almost a quarter of financial authorizations and nearly 40 percent of the exports the agency supported.

The lender authorized $20.5 billion during that fiscal year in low interest loans and other support for U.S. exporters and buyers of "Made in America" products.

The mislabeling of transactions, however, makes it difficult to tell exactly how the pie is divided. It extends to a Web site that allows lawmakers and others to check how Ex-Im supports businesses in each Congressional district.

The list of small businesses in Texas, for example, includes engineering giant Bechtel, which has 53,000 employees.

(Editing by David Chance and Tomasz Janowski)

By Howard Schneider and Krista Hughes