Sudan's foreign ministry on Saturday condemned the killing of 18 Sudanese people during an attack by an armed group from Chad, state media reported.
The killings took place Thursday when Sudanese herders from West Darfur state were ambushed while following the trails of camels looted by the Chadians the day before, according to Sudan's ruling Sovereign Council.
On Saturday, Sudan's acting Foreign Minister Ali al-Sadiq conveyed his country's "protest and condemnation of the incident", in a meeting with Chad's ambassador to Khartoum.
He also "demanded that Chad exerts an effort to arrest the assailants and to recover the stolen items," according to Sudan's official news agency SUNA.
Sudan has faced deepening unrest since army chief Abdel Fattah al-Burhan led a military coup in October last year. The putsch upended a transition to civilian rule put in place following the 2019 ouster of president Omar al-Bashir.
The power grab exacerbated political and economic turmoil in the country. The security situation has deteriorated, with a spike in ethnic clashes in Sudan's far-flung regions.
Thursday's incident sparked anger among Sudanese living in Geneina, the capital of West Darfur state near the border with Chad.
The deputy head of the Sovereign Council, Mohamed Hamdan Daglo, had on Thursday been in N'Djamena where he discussed border security in a meeting with Chad's leader General Mahamat Idriss Deby.
On Friday, Daglo called for restraint and vowed during the funeral of the slain Sudanese herders to take actions to bring "the chaos" along the border under control.
Daglo commands the powerful paramilitary Rapid Support Forces which emerged from the Janjaweed militia unleashed in Darfur by the government of then-president Bashir.
A Bashir ally, Ali Muhammad Ali Abd-Al-Rahman, is on trial at the International Criminal Court in the Hague for war crimes allegedly committed in Darfur roughly two decades ago when he was a Janjaweed commander.
Bashir is also wanted by the court.
Last month, Burhan pledged to step aside and make way for civilian groups to form a new government but Sudan's main civilian bloc dismissed the move as a "ruse".