Sudanese President Omar al-Bashir named a new military chief of staff Tuesday as his forces battle rebels in the Jebel Marra area of the western Darfur region, the defence ministry said.

Bashir issued decrees appointing "Lieutenant General Emadeddin Adawi to the post of joint chief of staff", the ministry said in a statement.

Adawi takes over from Lieutenant-General Mustafa Obeid Salim, who held the post from 2013 in what is usually a four-year assignment.

The decrees also appointed Lieutenant General Yahya Mohamed Khair as deputy chief-of-staff, as well as several other new nominations, but gave no reason for the changes.

The reshuffle came as Sudanese troops fight rebels from the Sudan Liberation Army led by Abdulwahid Nur in the Jebel Marra area of Darfur.

Tens of thousands of civilians are thought to have fled the latest clashes, which flared on January 15.

Ethnic insurgents in Darfur rebelled against Bashir's Arab-dominated regime in 2003 claiming they were being marginalised.

Bashir unleashed a campaign to crush them and was indicted by the International Criminal Court on war crimes charges relating to the conflict that the United Nations says has cost around 300,000 lives.

The military has also been battling the Sudan People's Liberation Army-North in South Kordofan and Blue Nile states since 2011, and last March, Khartoum committed troops to join the Saudi-led coalition against Shiite Huthi rebels in Yemen.