Keys, GaGa to sign off Twitter for charity

Stars including Lady GaGa, Usher and Justin Timberlake have joined a charity campaign backed by Alicia Keys.

The Digital Life Sacrifice campaign will be in aid of the Keep a Child Alive charity. Celebrities will be signing off social network services including Facebook and Twitter on Tuesday until the charity raises $1 million.

Keys said: "It's really important and super-cool to use mediums that we naturally are on."

According to The Associated Press other celebrities include Jennifer Hudson, Kim and Khloe Kardashian, Elijah Wood and Serena Williams.

Each celebrity will also feature in advertisements that will show them lying in coffins to signify their "digital deaths"

The singer added: "It's so important to shock you to the point of waking up. It's not that people don't care or it's not that people don't want to do something - it's that they never thought of it quite like that."