Clooney previously used his celebrity to highlight the Darfur crisis
Hollywood actor George Clooney is to present a telethon to raise money for the victims of the Haiti earthquake.
The event - which will feature pleas for cash from US celebrities - will be broadcast on MTV on 22 January.
Celebrity couple Brad Pitt and Angelina Jolie have pledged $1m (£612,000) from their charitable foundation to the Doctors Without Borders organisation.
Singer Madonna, meanwhile, has donated $250,000 to Partners In Health and has urged her fans to "act now".
"I urge all of my friends and fans around the world to join me collectively to match my contribution or give in any way you can," she said.
Tuesday's earthquake has left an estimated 50,000 dead on the Caribbean island.
Clooney and Madonna join a number of celebrities calling for donations to help the estimated three million injured and made homeless by the disaster.
Coldplay singer Chris Martin has asked for donations through Oxfam and the charity's global ambassador Scarlett Johansson has also appealed for contributions.
TV star Oprah Winfrey and actor Ben Stiller have both made appeals, while champion cyclist Lance Armstrong's LiveStrong Foundation has pledged $250,000 (£153,000) to help Haiti's recovery.
Haiti-born musician Wyclef Jean is also said to have raised more than $1m (£612,000) for the disaster relief effort.
The Hollywood Foreign Press Association, organisers of Sunday's Golden Globe awards in Los Angeles, have pledged $100,000 (£61,387) to Jean's Yele Haiti Earthquake Fund.