Obama talks frankly about US racial history amid Zimmerman verdict

President Obama has spoken for the first time since George Zimmerman was acquitted of the murder of unarmed black teenager Trayvon Martin, to praise the Martin family and reflect on the troubled racial history of his country.

Read: Obama calls the murder of black teen a 'tragedy'

Making a surprise appearance at the White House press briefing, the president made an emotional and uncharacteristically frank speech on the need for American's to do some "soul-searching" about the killing, speaking at length on the culture of racial prejudice experienced by a majority of African American men.

Watch: Anger in America after Zimmerman found not guilty

Obama spoke about the subconscious racial profiling and various forms of prejudice young black men suffer, and talked about his own experience as a young man being followed by department store security staff, and hearing drivers lock their door as he walked past.

Obama also talked about the need to change the "stand your ground" laws that facilitated Zimmerman's acquittal.

Watch: Demonstrators on LA streets over Zimmerman acquittal

Police initially did not charge Zimmerman because he said he was acting in self-defence. Florida's "stand your ground" law, in common with some other US states, allows the use of deadly force if a person feels their life is in danger. The president said:

Read: Key events in the Trayvon Martin shooting

After the details of the case became known, sparking outrage across America, charges were filed, but after a lengthy trial, Zimmerman was found not guilty.

U.S. Attorney General Eric Holder has said the Justice Department has an open investigation into the case. The department is looking into whether Zimmerman violated Martin's civil rights.

Obama's appearance mark his first extended comments on the Martin case, and the first time he has talked about his own experience of racial prejudice in the country he became the first African American president, back in 2008.