South Sudan rebel leader Riek Machar has said that any ceasefire called by the government must be credible and properly monitored.

South Sudan's government has agreed to an immediate end to fighting in a declaration welcomed by East African leaders in Nairobi. 

Mr Machar who is involved in a power struggle with President Salva Kiir said further negotiations were needed before a truce could come into effect.

He also called for more guarantees from the government.