South Sudan's warring parties attacked civilians, deliberately provoked violence, and torched homes and religious buildings in December and January, according to the latest report on ceasefire violations by the Intergovernmental Authority on Development (IGAD).

IGAD, which is monitoring violence by the warring parties, said that between 15 December and 31 January there were four major incidents in Nasser and Jamam in Upper Nile State that violated terms of the 23 January cessation of hostilities agreement between Salva Kiir and Riek Machar.

The first violation took place from 29 December to 3 January when SPLA-Juba and SPLA-In Opposition forces clashed in Nasser town near the UNMISS base and fired mortars over the Sobat River.

IGAD said government troops provoked the violence with "aggressive patrolling near SPLM/A (IO) areas and the burning of grass and tukuls," as well as attacks on civilians. However, IGAD noted that the rebels' response "went beyond what could be considered justifiable defensive measures."

In Jamam, IGAD said the rebels were responsible for attacking a disputed zone on 8 January, including attacking civilians.

Lastly, IGAD blamed the government for attacks on 19 and 21 January in Nasser: "On 19 January 2015 Government Forces deliberately burnt down a mosque near the airstrip. When returning to barracks from the airstrip they set fire to several buildings in the market. Another building was burnt on 21 January. The issue of Government Forces burning tukuls and other buildings has been going on since the start of the dry season."

UPDATE, 8 February 2015: In an addendum published after its original report, IGAD said that the SPLA-IO committed two additional ceasefire violations.

On 30 January 2015, the rebels "fired mortars from positions south of the Sobat River, initially at the Nasser airstrip and then towards the market place and the positions of GRSS Forces," IGAD said, while between 17 and 26 January, SPLA-IO forces attacked government positions around the town of Renk in Upper Nile state, inlcuding with mortar fire.

IGAD's full report and addendum is available for download below.