Former Enron chief executive Jeffrey Skilling was on Monday sentenced to more than 24 years in jail for massive fraud and conspiracy in one of the biggest scandals in US corporate history.

"Crimes of this magnitude deserve severe punishment," Judge Sim Lake said when handing down the sentence.

Skilling, 52, who had faced a maximum of 185 years in jail, told the court he planned to appeal his conviction stemming from the 2001 collapse of the Houston-based energy giant under shady deals.

"I am innocent of these charges," Skilling told the court.

Skilling's co-defendant in the fraud case, Enron founder Kenneth Lay, died of heart failure in July.