Sudan's army has refused to attend a regional bloc meeting aimed at putting an end to nearly three months of brutal fighting in the North African country.

The Intergovernmental Authority on Development (IGAD), an East African bloc, invited both the Sudanese army and the rival paramilitary Rapid Support Forces (RSF) to its meeting in Ethiopia's capital on Monday. However, Sudan’s army accused Kenya, which chaired the talks, of favoring the RSF.

The fighting in Sudan broke out in mid-April as a result of a power struggle between army chief Abdel Fattah al-Burhan and his former deputy, RSF commander Mohamed Hamdan Dagalo.

Dagalo did not attend the Addis Ababa talks in person, but the RSF sent a representative to the quartet meeting, which was attended by Kenya, South Sudan, Djibouti, and Ethiopia.

Following a meeting on Monday, the quartet issued a communique, deploring "the regrettable absence of the delegation of the Sudanese Armed Forces in spite of the invitation and confirmation of attendance." 

The quartet stated that it had agreed to "mobilize and concentrate the efforts of all stakeholders towards delivering a face-to-face meeting between the leaders of the warring parties." It also called on the rival generals to "immediately stop the violence and sign an unconditional and indefinite ceasefire."

The meeting came a day after UN Secretary-General Antonio Guterres warned that Sudan is on the verge of a full-fledged civil war, which could spread to neighboring countries and threaten regional stability.

Guterres "remains deeply concerned that the ongoing war between the armed forces has pushed Sudan to the brink of a full-scale civil war, potentially destabilizing the entire region," the UN chief’s spokesperson, Farhan Haq, said in a statement.

Residents reported battles and airstrikes in several areas of Sudan's capital city of Khartoum during the meeting, with some reporting rockets falling on civilians' houses.

Witnesses also reported fighting in El-Obeid, North Kordofan's capital and a commercial hub 350 kilometers (220 miles) south of Khartoum. According to the latest figures, around 3,000 people have been killed in Sudan's conflict so far.

According to the International Organization for Migration, nearly three million people have been displaced by the fighting, with nearly 700,000 fleeing to neighboring countries, particularly Chad and Egypt.