The head of WorldCom has said his company is co-operating with all the investigations into allegations of fraud and said the business was too big to fail.

The chief executive John Sidgmore promised he would investigate "every transgression".

We will release everything we know when we know it

John Sidgmore WorldCom

He denied accusations that WorldCom's statement about the company's $3.8bn (�2.5bn) accounting fraud was incomplete.

At a press conference, Mr Sidgmore said: "There remain many open questions, and quite a bit of speculation as to exactly what occurred.

"We will release everything we know when we know it."

Productive meeting

On Monday, WorldCom filed a sworn statement which Harvey Pitt, the head of the Securities & Exchange Commission (SEC), dismissed as totally inadequate.

The financial regulator said it was a chronology of events rather than an explanation of what had happened.

Mr Sidgmore said he had since held "highly productive" discussions with the SEC.

Billions of dollars available

WorldCom shocked investors last week when it announced that its chief financial officer had boosted company profits by improperly accounting for $3.8bn of expenses.

Its shares have dropped to just a few cents since the announcement and it is thought to be close to bankruptcy.

Bankruptcy could be ... in a matter of weeks if not less

Patrick Comack Analyst, Guzman & Co

But Mr Sidgmore said he hoped to have proposals for a financial restructuring this week.

He said WorldCom had $2bn in cash available and was talking to its banks about a $1bn funding package.

WorldCom is already facing a host of investigations and is likely to face numerous lawsuits and a criminal charge.

Two congressional committees have already demanded testimony and documents, while US President George W Bush has promised to bring those responsible to justice.

Shaken investors

WorldCom has been threatened with expulsion from the Nasdaq stock market this Friday, but the company said it would be appealing against the move.

Three years ago, WorldCom's shares traded at more than $60. On Tuesday they fell a further four cents to 10 cents.

"Bankruptcy could be much sooner than we expected, in a matter of weeks if not less," said Patrick Comack, analyst at Guzman & Co.

The WorldCom fraud follows scandals at energy giant Enron and its auditor, Andersen.

All three scandals - and the threat of more - have shaken investor trust in Wall Street's integrity and led to sharp share price falls.