South Sudan’s main opposition faction says it will challenge proposed amendments to the country's constitution.

The Sudan People’s Liberation Movement in Opposition (SPLM-IO) said it would petition continental bloc, the Inter-governmental Authority on Development (Igad), to stop the bill from reaching the justice ministry, the East African reported.

United Nations Miraya Radio reported that senior SPLM-IO official Oyet Nathaniel Penono said in the capital Juba on Thursday that Igad as guarantors of the South Sudan peace agreement should order the withdrawal of the bill or make significant amendments.

The South Sudan National Constitutional Amendment Committee (NCAC) submitted the proposed amendments to the constitution to the minister of justice last week.

However, the main opposition group insists amendments to the constitution are premature and fail to reflect the spirit of the September 2018 peace deal.

SPLM-IO objected immediately saying the NCAC should have waited until the transitional legislative assembly was reconstituted as per the peace agreement between President Salva Kiir and Dr Riek Machar, the leader of the SPLM-IO.

Another of the opposition’s grievances is that the issue of power devolution, and decentralisation in particular, has not been resolved.