US President Barack Obama's amazing grace points to injustices

President Barack Obama leads the congregation in song. Photo / AP

US President Barack Obama has led an impassioned funeral service for a popular black minister and politician killed in a church massacre in South Carolina.

Touching on the themes of racism, poverty and injustice that persist for African Americans in the US, Obama said the killing of Reverend Clementa Pinckney — a personal friend — and eight others in a church was a call to grace.

"Blinded by hatred, the alleged killer could not see the grace surrounding Reverend Pinckney and that Bible study group," Obama told thousands gathered in the arena of the College of Charleston.

"The alleged killer could have never anticipated the way the families of the fallen would respond when they saw him in court in the midst of unspeakable grief, with words of forgiveness," Obama said. Behind him stood dozens of purple-and-black-robed ministers of the African Methodist Episcopal church.

Amazing Grace was the theme of his 40-minute eulogy, which the president ended by leading thousands of voices in singing the traditional hymn.

He called his listeners to "prove" themselves worthy of this grace by waking up "to the way past injustices continue to shape the present", by considering what "causes so many of our children to hate".

And he said "God's grace" would be expressed by doing something about the 30 people cut down every day by gun violence.

Pinckney and the eight other black worshippers were slaughtered last week at the historic Emanuel African Methodist Episcopal Church in Charleston.

Their white alleged killer had joined the prayer and Bible service for an hour before shooting them.

Black politicians, rights activists and conservative Republicans pointed to the Confederate flag that still flew in an unofficial capacity at the state capital as a reminder of the South's history of slavery and "of systematic oppression and racial subjugation", Obama said.

Within days of the deaths, the flag started being pulled off the virtual and real shelves of Walmart, Sears, eBay and Amazon.com, and even the gift shops of some national parks.

South Carolina Governor Nikki Haley called for its removal from the state capital, and the state of Mississippi launched a move to remove its embedded image from its official state flag.

- AAP