Beyonce and Madonna join Haiti telethon

* Actor and organizer George Clooney to donate $1 million

* Beyonce to perform from London, Madonna from New York

LOS ANGELES, Jan 21 (Reuters) - Beyonce and Madonna have joined Friday's "Hope for Haiti Now" celebrity telethon for the earthquake-ravaged Caribbean nation, and actor George Clooney will donate $1 million to the cause, organizers said on Thursday.

Beyonce will perform in London and Madonna will take the stage in New York in the Friday evening benefit show which is being broadcast on all four leading U.S. networks, dozens of cable channels and internationally on Internet websites.

Clooney, the "Up in the Air" star who organized the event, will officially make his $1 million donation during the telecast, his spokesman said.

Clooney, who will take part from Los Angeles, told "Entertainment Tonight" he had been up for "three days straight trying to put it together."

"It's first getting networks together, getting phone lines, phone banks, charitable organizations together and finding the way to get the money to them. It's a long process of making deals and trying to get things done," he said.

Other notables taking part include former U.S. President Bill Clinton, U2 frontman Bono, singer Bruce Springsteen, rapper Jay-Z and actors Denzel Washington, Julia Roberts, Tom Hanks and Meryl Streep.

MTV, the show's co-producer, has said "Hope for Haiti Now: A Global Benefit for Earthquake Relief," will be the most widely distributed telethon in history. (Reporting by Alex Dobuzinskis: Editing by Cynthia Osterman)