By Theo Leggett BBC World Service business reporter

Earlier this week shares in the world's second largest carmaker fell to their lowest level in eleven years.

Falling car sales in the United States and growing doubts that it can meet its financial targets in a weakening economy now seem to be the least of Ford's problems.

Last week saw a sensational warning by the influential credit ratings analyst Sean Egan that the company was close to bankruptcy.

Too pessimistic?

Mr Egan told the BBC he believes Ford's debts may be getting out of control.

"They have approximately $11bn (�6.9bn) of shareholders equity as of the end of December and their debt is approximately $165bn so you don't have very much cushion," he said.

"But it gets worse in the sense that the unfunded pension liability is approximately $15bn, so if you're to make the adjustment in fact it would wipe out all that shareholders equity."

"The argument is made that you don't have to make the adjustment right away but that's assuming that the equity markets are going to go up substantially."

Mr Egan has a reputation as a particularly outspoken analyst, and claims to have drawn attention to financial problems at the fallen corporate giants Enron and WorldCom well before they became common knowledge.

Nevertheless not everyone agrees with his assessment. One UBS analyst actually raised his own rating on Ford on Wednesday, claiming that the market was being unduly pessimistic about the Blue Oval's prospects.

Difficulties 'overstated'

Karl Ludvigsen is a former vice president at Ford of Europe and now works for Euromotor Consultants. He believes Ford's problems have been exaggerated.

Is there a rift among Ford Motor executives?

"About $125bn of that debt is its financing business and of course that's a part of the business that's accustomed to rolling over debt and has ample access to sources of funding," he said.

"So if you hive that off, yes the unfunded pension aspect is a concern at Ford - it is for all the car companies - but again that's kind of rolling forward.

"The automotive business has $25bn in cash and its got $19bn in debt so the core car business doesn't look too vulnerable."

But Ford's difficulties are not just financial.

Analysts believe there is a growing rift between the president and chief operating officer, Sir Nick Scheele, and his likely successor, the executive vice president David Thursfield.

Such rumours gained ground this week when the company publicly overturned Sir Nick's decision to award all it's advertising work to one agency, WPP - a firm run by a personal friend of his.

Sir Nick has dismissed the rumours as scurrilous but with the markets already nervous of Ford's prospects, they are unlikely to help his credibility, or the company's share price.