U2 are among more than 150 musicians who have joined the “I`m gonna be your friend” social media campaign, backing a fundraising effort to help people affected by the drought in northeast Africa.

Universal Music Group, Facebook, Yahoo!, AOL, MSN, YouTube, Twitter and celebrities including Lady Gaga, U2, Eminem, Muhammad Ali, Jennifer Lopez, Elton John, Britney Spears, Madonna, Justin Bieber, Sting, and Rihanna are backing the campaign, via their huge networks of friends and fans on Facebook and Twitter.

The celebrities are asking people to pay to download a single by Bob Marley & The Wailers for $1.29, the campaign official site imgonnabeyourfriend.org said.

Visitors to the site are also encouraged to donate money and share information about the campaign in social networks and blogs.

Bob Marley & The Wailers’ 1973 song High Tide or Low Tide has been donated by the reggae star’s family, and appears on the site with footage of malnourished children.

“Bob’s music has always conveyed a message of hope, unity and love. And this is a message needed now more than ever,” campaign organizers said on the website.

The campaign hopes to increase the number of participants to a billion people.

About 3.6 million people are at risk of starvation in Somalia and 12 million people across the Horn of Africa, the United Nations says. Thousands of families, including around 70,000 children, have been forced to flee their drought-stricken homes, with many now in overcrowded refugee camps.