Former US president Jimmy Carter is stepping in to help resolve a legal battle over the Martin Luther King's travelling bible and 1964 Nobel Peace Prize.

The assassinated civil rights leader's estate is controlled by his sons, who last year asked a judge to order their sister to surrender the items.

The Herald:

In a board of directors meeting last year, sons Martin Luther King and Dexter Scott King voted 2-1 against Bernice King to sell the two artefacts to a private buyer.

In May the judge in the case ordered the two sides into mediation after lawyers for both sides said they were close to an agreement and Bernice King's lawyers asked for mediation.

Mr Carter, 91, said he met the Kings at the Carter Centre in Atlanta, Georgia, and the three siblings issued a statement expressing optimism about a resolution.