May 3 (Reuters) - AGL Energy on Tuesday backed its plan again to demerge itself, a day after tech billionaire and climate activist Mike Cannon-Brookes unveiled a 11.28% stake in Australia's biggest power producer and said he would vote against it.

Cannon-Brookes, in a letter released on Monday, called AGL's plan to split into two companies "flawed", even as the company maintained it was in the best interest of its shareholders. (Reporting by Shashwat Awasthi; editing by Uttaresh.V)