NEW YORK (Reuters) - Shares of insurance giant American International Group Inc rose as much as 33 percent, buoyed by the company's improving relations with former long-time CEO Maurice (Hank) Greenberg.

"I think it's the notion that there's a reconciliation underway between Greenberg and the company," said Bill Bergman, a Chicago-based senior analyst for Morningstar Inc.

AIG's new chief executive, Robert Benmosche, told Reuters in an interview that he had turned to Greenberg for help and support and has been in regular contact with him.

"I want to get the benefit of his criticisms or his support," Benmosche said.

"The world may choose to vilify him. I think of him as having had some problems, but he can help us with the solutions."

Greenberg, in a separate interview by phone, said: "If Bob Benmosche seeks any assistance, whatever he needs me to do, I'll be glad to give him."

Greenberg, 84, who built AIG into the world's largest insurer, resigned from the company in 2005 amid an accounting scandal and has had icy relations with the firm ever since.