Former Enron chief executive Jeffrey Skilling took the witness stand in his own defence yesterday, proclaiming his innocence and telling the jury that he never imagined the company he helped create would collapse.

Mr Skilling (52), and former Enron chief executive and chairman Ken Lay stand accused of lying to investors and analysts to hide the dismal financial health of Enron, which collapsed in December 2001 in the then largest-ever US bankruptcy.

"It's not in my nature not to fight something like this. The charges against me are wrong," a visibly nervous Mr Skilling testified. "I will fight those charges till the day I die."

Legal experts have said Mr Skilling's testimony at the trial will be a crucial factor in whether he is convicted of the 28 counts of conspiracy, fraud and insider trading lodged against him.

Under questioning from his lawyer Dan Petrocelli, Mr Skilling talked about his love for the company that he helped build from a sleepy Houston pipeline company into an international trading giant, and his decision to resign as chief executive less than six months after taking up the post. "I was exhausted ... my head just wasn't in it anymore," he said.

Mr Lay, Mr Skilling's co- defendant in the case, returned to the chief executive position he had previously held for 15 years after Mr Skilling's departure. He is expected to testify later in the trial, in which he faces six charges of conspiracy and fraud.

Both men have pleaded not guilty, and face decades in prison if convicted at the trial that began at the end of January.

Enron's demise was the first in a wave of corporate scandals that shook the financial world and eventually prompted stricter disclosure rules for companies.

Mr Petrocelli asked Mr Skilling whether at the time of his August 2001 departure, less than four months before the company would tumble into bankruptcy, he believed Enron would collapse.

"Not in my wildest dreams. It's almost inconceivable now that it happened," he said.

A $1 billion (€826 million)charge Enron announced in October 2001 did not trouble him, Mr Skilling said, since he believed the company was using his departure "to clean things up".

But a negative story in the Wall Street Journal the following day and several subsequent articles highlighting the dubious deals Enron had undertaken with partnerships operated by former chief financial officer Andrew Fastow put pressure on Enron's already weak stock. "I believed strongly the transactions were appropriate and proper," Mr Skilling said.