WASHINGTON (Reuters) - Conservative activist Andrew Breitbart, a larger-than-life author and publisher, died early on Thursday at the age of 43, the Los Angeles Coroner's office said.

The writer and blogger, who was influential in U.S. Republican politics, was the center of several major news websites, including www.Breitbart.tv, www.breitbart.com and www.biggovernment.com.

Larry Bietz, the watch commander at the coroner's office, said it had received a report that Breitbart died at UCLA Medical Center but that the office had not yet received his body. "I can confirm that it's been reported to us that he died," he said.

A page on his websites said Breitbart "passed away unexpectedly from natural causes." A representative for breitbart.com confirmed his death in an e-mail.

(Reporting By Susan Heavey; Editing by Anthony Boadle)