The brother of George Floyd has delivered an impassioned plea for a US congressional panel not to let Mr Floyd’s death in Minneapolis police custody to have been in vain.

“He didn’t deserve to die over $US20,” Philonise Floyd, 42, said in an opening statement to a House Judiciary Committee hearing on proposed changes to police practices and accountability.

Speaking on Thursday morning (Australian time) – more than two weeks after Mr Floyd died – his brother broke down at the witness table while describing how they had not been able to say goodbye.

“I’m here to ask you to make it stop. Stop the pain,” Mr Floyd said.

“It is on you to make sure his death is not in vain.”

The US House of Representatives Judiciary Committee held its first formal proceedings to examine issues underlying weeks of US civil unrest as it considered sweeping reform legislation.

Mr Floyd was unarmed when taken into custody outside a corner market where an employee had reported that a man matching his description tried to pay for cigarettes with a counterfeit bank note.

“I’m asking you, is that what a black man’s worth? $US20? This is 2020. Enough is enough,” Mr Floyd, who buried his brother on Wednesday, told the politicians.

“George called for help and he was ignored. Please listen to the call I’m making to you now, to the calls of our family and the calls ringing on the streets of all the world.”

Philonise Floyd and House Speaker Nancy Pelosi at the hearing. Photo: AAP

The emotionally charged hearing had politicians and witnesses expressing sorrow at Mr Floyd’s May 25 death, the latest in a long string of killings of African-American men and women by police that have sparked anger on the country’s streets and fresh calls for reforms.

“Justice for George,” Mr Floyd said on his way into the hearing venue.

The judiciary committee is preparing to support a broad package of legislation, aimed at combating police violence and racial injustice, to the House floor by July 4. It is expected to hold further hearings next week to prepare the bill for a full House vote.

“While we hold up human rights in the world, we obviously have to hold them up in our country,” said Representative Karen Bass, chairwoman of the Congressional Black Caucus, which wrote the legislation.

Representative Jim Jordan, the committee’s top Republican, said “the American people understand it’s time for a real discussion, real debate, real solutions about police treatment of African-Americans”.

-with AAP