NEW YORK - Roger Ailes, who built Fox News into a politically powerful cable giant that helped redefine US television news, has died, the network announced.

The Fox co-founder, who was also a consultant to Republican presidents, was ousted from the network last year under the cloud of a series of sexual harassment allegations.

The network's hosts struggled to hold back tears as they read a statement from Ailes' wife Elizabeth announcing his death at the age of 77.

A longtime confident of media titan Rupert Murdoch, Ailes was a central figure in the conservative US political movement.

He resigned in July after a sexual harassment lawsuit from former Fox news host Gretchen Carlson.

His wife's statement, first published on the conservative Drudge Report, said: "I am profoundly sad and heartbroken to report that my husband, Roger Ailes, passed away this morning."

Ailes, she said, "was a loving husband to me, to his son Zachary, and a loyal friend to many. He was also a patriot, profoundly grateful to live in a country that gave him so much opportunity to work hard, to rise - and to give back."

Under the leadership of Ailes, Fox became the most widely watched cable news channel, home to key conservative political commentators and drawing an audience distinct from rivals CNN and MSNBC.

Ailes served as a consultant to presidents from Richard Nixon to Ronald Reagan to George H.W. Bush and according to some analysts helped revive conservative politics in the United States.

"Apart from the presidents he served, he was arguably the single most important figure in the creation of modern conservatism," David Greenberg, a Rutgers University political scientist, wrote in an essay for Politico last year.

Agence France-presse