NEW YORK (CNN/Money) - A former employee at WorldCom's London unit alleges she tipped off British authorities to possible accounting fraud at the company as far back as 1999, but the warning never made it to U.S. regulators, according to a published report Tuesday.

Geraldine Kelly, a former WorldCom bookkeeper, provided the U.S. House Energy and Commerce Committee with a sworn affidavit claiming she alerted Britain's Department of Trade & Industry to accounting fraud at WorldCom's London office in 1999, according to the Wall Street Journal.

After disclosing an additional $3.4 billion in accounting irregularities earlier this month, which brought its total misstatement to $7.2 billion, WorldCom said $217 million of the irregularities came from 1999.

Kelly left WorldCom in 1999, but accounts vary on whether she was fired or left of her own accord. If she was fired, as one person involved with the House investigation told the paper, it could raise questions about the nature of her testimony.

Memos from another London office executive released earlier this summer warned senior WorldCom officials and the company's former auditor, Arthur Andersen, that the company was overstating profits, but no action was taken, according to the Journal.