An autopsy has shown no evidence of foul play in the heart attack death of Kenneth Lay, the disgraced head of Enron Corp who had been convicted over one of the worst corporate collapses in the United States.

Lay, 64, died on Wednesday while holidaying near Aspen, Colorado, six weeks after being found guilty of fraud and conspiracy.

The former chief executive who had been awaiting sentencing, faced decades in prison in connection with Enron's 2001 bankruptcy.

"There was no evidence of foul play," said Dr Rob Kurtzman, the forensic pathologist who performed the post mortem examination.

"The cause of death is coronary artery disease," he said, adding that the examination showed that Lay had previously suffered a heart attack.