Mourners in Minnesota are due to attend an emotionally charged memorial service for George Floyd, an African American man whose death in police custody more than a week ago has triggered global protests.

Minneapolis is set to hold a memorial service for George Floyd, the black man whose death in police custody has sparked protests across the United States.

The protests dwindled overnight after prosecutors on Wednesday levelled new and elevated charges against four Minneapolis police involved in Mr Floyd's death.

Another bystander video has shown a US police officer pressing his knee into the neck of a handcuffed black man, which has prompted an investigation and promises of transparency.

The officer who placed his knee on Mr Carroll's neck has been placed on administrative leave, the department said.

Officials in Minneapolis say the looting and property damage that following the death of George Floyd has caused at least $US55 million ($79 million) in damage.

Brees who won the SuperBowl in 2009 with the New Orleans Saints season, was criticised by fellow high-profile athletes and others in the wake of George Floyd's death.

"In an attempt to talk about respect, unity, and solidarity centred around the American flag and the national anthem, I made comments that were insensitive and completely missed the mark on the issues we are facing right now as a country," he wrote