Chrysler LLC Chairman and CEO Bob Nardelli has said he will step down as head of the company after it completes its time in Chapter 11.

"I announced to Chrysler's Board of Management and our senior leadership as well as the US Treasury that I plan to leave the company and return to Cerberus Capital Management as an adviser," Nardelli said in a letter to employees.

Fiat's mercurial boss, Sergio Marchionne, is expected to become chief executive of the new Chrysler, which will be run by a new nine-person board.

Nardelli said the US Treasury Department did not ask him to step down; it was his decision. "I felt it was an appropriate time," he said.

"I will work closely with all of our stakeholders to complete the restructuring and see that this new company swiftly emerges with a successful closing of the alliance," Nardelli said.