Khartoum (AFP) - Sudanese President Omar al-Bashir has declared a four-month ceasefire in two states of Blue Nile and South Kordofan, where recent fighting between troops and rebels has left scores of casualties, the army said Friday.

Bashir's forces have been battling the rebel Sudan People's Liberation Movement-North (SPLM-N) in the two states since 2011, and neither side has decisively gained an upper hand in the fighting.

"President Bashir announced four months of ceasefire in Blue Nile and South Kordofan starting from Saturday," army spokesman Brigadier Ahmed Khalifa al-Shami told AFP.

"This gesture of goodwill from the government is to give the armed groups a chance to join the peace process and to surrender their arms."

The ceasefire was anticipated ahead of the start of the rainy season that leaves roads in the these regions impassable.

Khartoum limits press access to the war-hit border regions, making it nearly impossible to verify the often-contradictory reports from the army and the SPLM-N about fighting there.

Bashir had announced a similar ceasefire in South Kordofan, Blue Nile and the western Darfur region -- the scene of a separate insurgency -- in late 2015 and extended it by a month at the beginning of this year.

But new fighting in Blue Nile and South Kordofan erupted after the end of that ceasefire earlier this year.

Shami said the latest ceasefire starting from Saturday does not extend to the war-torn area of Darfur as "there was no real rebellion now in Darfur".

"There are only small groups that are trying to disturb the security in Darfur. Sudanese forces have ended the rebellion in Darfur."

Sudan held a referendum in Darfur in April, with officials saying almost 98 percent of voters opted for retaining the region as five separate states.

Darfur has been gripped by conflict since 2003, when ethnic minority rebels rose up against the government in Khartoum.

Bashir launched a brutal counterinsurgency and at least 300,000 people have been killed, the United Nations says. Another 2.5 million have fled their homes.

Bashir is wanted by the International Criminal Court on war crimes charges related to Darfur, which he denies.