New York (AFP) - Rap mogul Jay Z has quietly used his wealth to post bail for people arrested in protests across the United States against police excesses, an author close to him said.
Dream Hampton, a writer and activist who worked with Jay Z on his 2010 memoir "Decoded," made the revelations in a series of messages on Twitter that she later deleted but were reproduced by the hip-hop magazine Complex.
"When we needed money for bail for Baltimore protesters, I... hit Jay up, as I had for Ferguson (and he) wired tens of thousands" of dollars within minutes, read one tweet.
She also tweeted that Jay Z and his pop superstar wife Beyonce wrote a "huge check" to support the burgeoning "Black Lives Matter" movement aimed at improving police treatment of African Americans.
Protests spread last year after a white police officer shot dead unarmed African-American teenager Michael Brown in the St. Louis suburb of Ferguson.
Major demonstrations, some turning violent, erupted in recent weeks in Baltimore after another African-American man, Freddie Gray, died from a spinal injury sustained in police custody.
Hampton later wrote that she deleted the tweets because Jay Z "would be pi-issed to see I was offering evidence" that he is taking action.
The tweets appeared aimed at defending Jay Z and Beyonce, who have faced accusations from some activists that they have only paid lip service to causes without tapping into the couple's estimated $1 billion net worth.
One prominent critic has been Harry Belafonte, the calypso music giant who supported Martin Luther King's family financially during the Civil Rights Movement.
In a 2012 interview with The Hollywood Reporter, Belafonte said that contemporary celebrities "have turned their back on social responsibility" and singled out Jay Z and Beyonce.
- 'Greatest form of giving' -
Jay Z, who grew up poor in New York City, has made no secret of his concern about police actions.
In December he met New York Governor Andrew Cuomo to press for criminal justice reform and was earlier reported to have set up a fund for the education of the children of Sean Bell, an African American shot dead by police on his wedding day in 2006.
In 2003, Jay Z set up the Shawn Carter Foundation -- using his real name -- which according to its website has provided $2.9 million in scholarships and other initiatives to support higher education for people facing hardship.
But Jay Z and Beyonce -- among America's most recognizable faces -- have mostly avoided public events.
Jay Z discussed his thinking in his song "Nickels and Dimes," in which he raps of giving money to an addict and reflects, "Did I do it for him or do it for myself? / Can't lie to myself."
"The greatest form of giving is anonymous to anonymous," he concludes in the song.
Jay Z and Beyonce met Brown and Gray's families last week at a peace concert in Baltimore by Prince but left without making public appearances.
One exception to the low profile is politics. The power couple have been strong supporters of President Barack Obama, throwing a party during his 2012 re-election campaign that raised an estimated $4 million.
Jay Z has been most in the news lately for spending $56 million to buy the music streaming service Tidal, which he has relaunched with fellow stars.
He performed a concert in New York on Saturday in an exclusive for Tidal. In a freestyle segment, he belittled rivals Spotify and Apple -- and paid homage to Brown and Gray.