Kenya's president had said he will not let the conflict in neighbouring South Sudan descend into genocide, though he stopped short of spelling out any action to end the increasingly ethnic slaughter.

Four months of fighting between government and rebels in the world's newest nation has raised fears of a wider conflict that could further destabilise a fragile region and send hundreds of thousands more refugees over borders.

Uganda, another neighbour of oil-producing South Sudan, has already sent in troops to back the government.