South Sudan's troubled ruling party is trying to pull itself together ahead of a new round of peace talks on the country's civil war, with high-profile assistance from Egypt and Uganda.

The attendance on Thursday of Egyptian Foreign Minister Sameh Shoukry and Ugandan President Yoweri Museveni comes amid reported friction inside the administration of South Sudan President Salva Kiir.

Kiir has faced recent calls for his resignation as international frustration rises with the five-year civil war in the East African nation.

His administration has been marked by the departures of several high-profile officials who accused their former colleagues of blocking the path to peace and profiting from the conflict.

The ruling party says even the opposition was invited to its discussions this week but the opposition refused.