South Sudan government troops tried to force their way into a United Nations compound where thousands of civilians were sheltering from violence in the country, the UN said.

Senior government figures and troops threatened staff when they tried to enter the UN compound in Bor, said Martin Nesirky, the spokesman for UN secretary-general Ban Ki Moon.

Bor has been repeatedly lost and retaken by government forces in the worsening conflict between President Salva Kiir and his former vice-president Riek Machar.