Some 300 protest rallies were held worldwide Friday ahead of a last-ditch parole board hearing for death row inmate Troy Davis, whose planned execution sparked an international movement.

Davis is set to be executed September 21 for the 1989 shooting death of a police officer in Savannah, Georgia, but his supporters say there is strong evidence supporting his claim of innocence.

On Thursday, petitions with 663,000 names were handed to the Georgia Board of Pardons and Paroles urging clemency. The board convenes Monday to consider the case.

Laura Moye, the Death Penalty Abolition campaign director for Amnesty International USA, said a march was planned in downtown Atlanta at 6:00 pm Friday (2200 GMT) followed by a service at Ebenezer Baptist Church, the spiritual center of the civil rights movement in the 1960s under Martin Luther King.

She said rallies for Davis started earlier in Hong Kong and carried on throughout the day in the United States, Latin America, Europe and Asia.

Moye said there were 10 events in France on behalf of Davis, who is scheduled to die by lethal injection next week at a prison in Jackson, Georgia, south of Atlanta.

The parole board is made up of five members and it takes just a simple majority to decide a case.

"We hope the message they hear is that there is too much doubt in this case," Moye said. "Can we even rely on the conviction of Troy Davis? Can we be sure we are not going to execute someone who is innocent?"

In the more than two decades that he has been in jail for the murder of white police officer Mark Allen MacPhail, Davis, who is African-American, has maintained his innocence.

Additionally, seven out of nine witnesses who gave evidence at his trial in 1991 have recanted or changed their testimony.

No murder weapon was ever found, no DNA evidence or fingerprints tie Davis to the crime, and other witnesses have since said the murder was committed by another man -- a witness who testified against him.

The case has became internationally famous as the face of what critics call a corrupted justice system in the US deep South, with a black man wrongly and hastily convicted of killing a white officer.

American Civil Liberties Union attorney Tanya Greene said the events will carry on over the weekend.

"There is a great mobilization, this is more than I have known in recent history... because it's so clear that he was railroaded, the witnesses lied. We have all the evidence now," she said.

The petitions delivered to the Georgia parole board included signatures from 26 former death row prisoners who were exonerated of their crimes.

The US Supreme Court became involved in 2009 and ordered a federal judge in Savannah to convene a hearing to consider new evidence.

In August 2010, however, the district court in Georgia ruled that Davis had failed to prove his innocence and denied him a new trial. The top US court turned down a subsequent appeal.