When in 2011 South Sudan broke away from Sudan becoming the world's newest nation following two decades of civil war, the Sudan People's Liberation Movement (SPLM) emerged as the ruling party of the newly-born country.

However, some members of the movement – whose armed wing, the Sudan People's Liberation Army (SPLA), long fought for the autonomy of southern Sudan – did not relocate to the new state. Instead, they regrouped into the SPLM-North (SPLM-N) and continued their fight against the central government of Omar al-Bashir in Sudan.

The SPLM-N – banned by the Sudanese government and branded as a rebel movement – has been fighting Sudanese forces in the Blue Nile and South Kordofan states since its very formation in 2011.

Blue Nile and South Kordofan conflict

Shortly after the independence of South Sudan, violence erupted in the two states. The SPLM-N took up arms against government forces in protest against the fact that the two states were not allowed to take part in the January 2011 referendum on the creation of South Sudan and a perceived lack of democratic elections.

SPLM-N accuses Sudan of marginalising the non-Arab population in the two states. In turn, Kharthoum claims SPLM-N carries out attacks on civilian areas indiscriminately and "disrupts civilian life."

"The conflict is the result of social, economic, cultural and political marginalisation and a lack of equal citizenship, aggravated by the narrow political Islam of the ruling National Congress Party (NCP),"Yassir Arman, SPLM-N secretary general, told IBTimes UK.

"The civilian population and the SPLM-N have been under attack for the past six years from the government, which denied humanitarian access to more than one million civilian in the two areas. This is a war crime.

"Gen Bashir thought he would crush the SPLMN totally and he failed. We are a secular movement that stands for a new Sudan, we have a just cause and demand for democratisation, equal citizenship and equal rights for all," he continued.

The conflict, sometimes dubbed as the Third Sudanese Civil War, has caused the death of between 600 and 1,500 people and the displacement of more than 1.2 million civilians.

In September, the Sudanese government was accused of using chemical weapons against civilians in Darfur, where at least 300,000 people have been killed since a conflict erupted in 2003, resulting in the International Criminal Court (ICC) attempt to try Bashir for alleged war crimes in Darfur. He has denied the charges.

Arman alleged the Sudanese government is using chemical weapons in Blue Nile and South Kordofan as well and called on an imminent investigation.

"The silence of the UN and the international community encourages the government This is not acceptable," he said.

Sudan' s position

In June 2016, Sudan declared a four-month ceasefire in Blue Nile and South Kordofan "to give the armed groups a chance to join the peace process and to surrender their arms."

Khalid Al-Mubarak, media attache at the Sudan embassy in London, told IBTimes UK the SPLM-N, which is affiliated with Darfuri rebels, aims to reject peace talks in order to "keep US sanctions in place".

"They refused all government concessions for humanitarian access insisting that aid should be channelled through other countries. In the past, they and their supporters have used the UN's Operation Lifeline Sudan to smuggle weapons and feed armed groups. They would like to repeat that," he claimed.

Mubarak also denied allegations of chemical weapons being used in the conflict zones and claimed the Amnesty's report was "hastily-written and based on telephone conversations with rebels."

"Yasir Arman does not have a just cause. As a result of the National Dialogue (which was welcomed by the West) the government is offering continuation of the democratisation process and fundamental changes in the structure."