A legal fight between Martin Luther King Jr.'s heirs over who owns the slain civil rights leader's 1964 Nobel Peace Prize medal has been settled, but the terms were not immediately known, a judge said in an Atlanta court.

A trial to settle the years-long dispute over the medal had been set to start on Monday. It would have pitted King's two sons against his surviving daughter, who have disagreed over whether the item should be sold.

The three siblings serve as directors of a corporation formed to manage the estate of King, who had no will when he was assassinated in 1968 by a white supremacist in Memphis, Tennessee.

Martin Luther King III and Dexter King voted in January 2014 to sell the medal and a Bible their father carried during the civil rights movement in the 1960s. Bernice King objected to a sale, calling the heirlooms "sacred" to the family.

Superior Court Judge Robert McBurney had ordered the items to be kept in a court-controlled safe deposit box pending the outcome of the lawsuit.

McBurney said in court today that he would turn over the keys to the box to Martin Luther King III, the chairman of the estate board, as requested by both parties in their joint motion to dismiss the lawsuit.

The judge said he did not know details of the settlement.

Lawyers for the estate and Bernice King were not in court and could not immediately be reached for comment.

Last month, McBurney ruled that the Bible, which US President Barack Obama used in his second inauguration, belonged to the estate.

Former President Jimmy Carter was one of the mediators who had worked to secure a resolution of the lawsuit. Prospects for a settlement had been described as fair to poor, according to a court summary.

In its lawsuit against Bernice King, the estate said she signed a 1995 agreement giving control of King's possessions to the estate. But she said the estate never sent her a list of items to be turned over, as required in the settlement of a lawsuit over that agreement.