The United Nations is turning to social media to raise money and awareness of humanitarian crises that have fallen off the global agenda, said U.N. Undersecretary-General Valerie Amos.

The United Nations will unveil the social media campaign on Monday during World Humanitarian Day, the organisation's annual day to remember aid workers who have died while in the field and promote humanitarian aid.

"Basically what happens every year, there are crises that hit the spotlight (and) Syria is at the top of the agenda right now," Amos, who also is the United Nations' emergency relief coordinator, told Reuters. "There are places like Afghanistan, Yemen, Haiti, Colombia, which continue to have humanitarian need but which may have slipped off the global agenda."

Under the slogan "The World Needs More," the campaign has partnered with entertainers and corporations to raise funds on social networks such as Twitter.

Entertainers working with the program will tweet a word such as "strength," "love" or "humanity," and a corporate sponsor will donate $1 to a U.N. humanitarian fund for every retweet.

"We're going to try to put any funding that is raised, any money raised into those countries where are appeals are under-funded," Amos said.

Those who will participate include American pop singer Beyonce, Indian film actor Amitabh Bachchan, Brazilian novelist Paulo Coelho and 10-year-old American comedian Kid President.

Corporate sponsors include U.S. financial services company Western Union, British bank Barclays, Italian fashion house Gucci, computer chip maker Intel and the Sergio Vieira de Mello Foundation.

The U.N General Assembly in 2008 declared August 19 World Humanitarian Day as a way to mark the 22 U.N. and aid agency workers, including Special Representative of the Secretary-General to Iraq, Sergio Vieira de Mello, who died during a 2003 bombing of the organization's Baghdad headquarters.