Justin Bieber - Stars Support World Humanitarian Day

Beyonce teamed up with United Nations officials earlier this month (Aug12) to launch the initiative, which encourages people to give back by getting involved in charity ventures.

She allowed U.N. chiefs to use her track I Was Here to mark the global event - and now her pop star peers have rallied behind the campaign.

In a post on her Twitter.com page, Rihanna ‏writes, "Do something good for someone today. 1Day 1World 1Message 1Love", while Bieber adds, "I am supporting the UN for World Humanitarian Day."

Actor Hugh Jackman proclaimed, "It's World Humanitarian Day and I'm doing something good, somewhere, for someone else. Join in!", while Oprah Winfrey ‏offered, "I am signing up and supporting the UN and Beyoncé in doing something good for Whd2012", and Adele pleaded, "Do something good for someone".

Singers Shakira, Kelly Rowland and Santigold also declared their support, while Gaga tweeted, "I'm supporting & sending love to Beyonce & the UN for World Humanitarian Day."