The jury reached a verdict finding Lay guilty of all six counts that were pressed against him. On separate charges of bank fraud a judge has convicted Lay to 165-year prison term, while Skilling, found guilty of 19 of the 28 charges of fraud, could face 185 years behind bars.

The jury also found Lay and Skilling guilty of having repeatedly lied to cover up accounting mis-reporting and failing ventures at Enron. The verdict was pronounced after a week of deliberations following the trial, which lasted nearly four months.

Lay and Skilling have been ordered to post a $5-million bond, while Lay will have to surrender his passport to the court pending sentencing in September 2006.

Lawyers for both Lay and Skilling said they would appeal the verdicts.

Once America's seventh largest company, Enron collapsed after accounting frauds were revealed against it. The company had hidden an estimated $40 billion of debts in secret accounts to protect its core balance sheet.

Enron had more than $68 billion in market value before its bankruptcy wiped out more than 5,000 jobs and at least $1 billion in retirement funds.

Among the government''s witnesses were accountant Sherron Watkins, whose internal warnings had been ignored, and the former head of investor relations, Mark Koenig.

The trial pitted former colleagues against one another. Former finance chief Andrew Fastow, who will serve a reduced 10-year sentence for confessing having helped orchestrate the fraud, and siphoning-off $45 million for himself in the process.

The Enron trial, the most high-profile case in a succession of corporate scandals that have emerged in recent years that have seen executives from giants such as WorldCom and Tyco sentenced to jail terms.