Global Crossing was forced to delay its results
The deficit comes from a huge write down of the company's assets.
Global Crossing operates a worldwide network of fibre optic cables, which link more than 200 cities in 27 countries.
The company filed for bankruptcy protection last month, following several months of speculation about the company's financial position.
'Significant' write-off
Global Crossing said the write down would mean it would post a "significant net loss" for both the fourth quarter and 2001 as a whole.
The write-off reflected "remaining goodwill and other identifiable intangible assets (approximately $8bn) as well as a multi-billion dollar write-down of its tangible assets."
The company was due to release its fourth quarter results on Tuesday, but instead issued only revenue estimates.
It said it expected to post revenues of about $804m for the final three months of 2001, and revenues from continuing operations of $3.2bn for the whole year.
Funding problems
Meanwhile Asia Global Crossing, which is part-owned by the US company, said it expected to post a "material " loss for the last three months of 2001.
The company - which was not included in last month's bankruptcy filings - also said it lacked enough funding to cover its business plan.
But it said it had hired investment bank Lazard Freres to help it consider its options as it tries to raise extra funding.
Asia Global Crossing also said it had hired outside lawyers to investigate allegations of questionable accounting practices.
The US Securities and Exchange Commission (SEC) is already looking into claims that Global Crossing may have falsely boosted revenues by swapping network capacity.
Rise and fall
Global Crossing was regarded as one of the most promising of the new generation of telecoms companies which sprung up in the late 1990s.
But a combination of the economic slowdown, increased competition and heavy debts hit the company hard.
Last month it filed for bankruptcy protection in what was the fourth largest insolvency in US history.