The unilateral ceasefire in Nuba Mountains and Blue Nile declared last month between SPLM-North and Sudan government ended on Monday.
The ceasefire was a result of floods caused by heavy rains in September and meant for delivering humanitarian aid to citizens.
SPLM-N Secretary-General Yasir Saeed Arman confirmed the end of ceasefire and revealed a plan to begin advocating for the rights of Nuba Mountains and Blue Nile.
He accused the government of failing to protect civilians from floods effects and instead blocked humanitarian organizations from delivering aid to victims.
Mr Arman claimed that during the period of unilateral ceasefire, Sudan Armed Forces or SAF continued to bomb civilians in SPLM-N controlled areas.
He urged the SPLA-N forces to unite and cooperate with Sudan Revolutionary Front to overthrow Khartoum regime.
CRN could not verify the claims.