RIYADH (Reuters) -Sudan's warring army and Rapid Support Forces paramilitary will resume talks on Sunday, a senior Saudi diplomat said, as air strikes and heavy fighting raged overnight around Khartoum despite an agreement to protect civilians.

Saudi Arabia, which has been hosting the talks aimed at securing a ceasefire deal, has also invited army chief Abdel Fattah al-Burhan to Friday's Arab League summit in Jeddah, the diplomat said.

The conflict that broke out suddenly a month ago has killed hundreds, sent more than 200,000 people into neighbouring states, displaced another 700,000 inside the country and risks drawing in outside powers and destabilising the region.

Despite Burhan's invitation to the Jeddah summit, he is not expected to leave Sudan for security reasons, two other diplomats in the Gulf said.

Burhan was invited because he is head of Sudan's Sovereign Council that was meant to be overseeing a planned transition to civilian rule before the conflict erupted, the Saudi diplomat said. His rival RSF chief Mohamed Hamdan Dagalo, known as Hemedti, is deputy head of the council.

"We haven't yet received the names of the delegation, but we are expecting Sudan to be represented in the summit," the Saudi diplomat said.

The two sides agreed on Thursday to a "declaration of principles" to protect civilians and allow humanitarian access, but there has been no let up in the fighting, with clashes and strikes ringing around Khartoum and neighbouring areas.

In the resumed talks in Jeddah, the sides will start by discussing mechanisms to implement Thursday's agreement including plans for aid delivery, safe corridors and the removal of forces from civilian areas.

Talks would then move onto ways to end the conflict, eventually paving the way for a civilian government. "The nature of the conflict affects the dialogue. Yet I found a very good spirit from both sides," the Saudi diplomat said.

In public neither side has shown any sign it is willing to compromise and they battled through previous truces. Although the RSF has promised to uphold Thursday's agreement, the army has not yet commented on it.

Neither side seems able to secure a quick victory, with the RSF dug into residential districts throughout the capital and the army able to call on air power.

(Reporting by Aziz El Yaakoubi and Nafisa EltahirWriting by Angus McDowall Editing by Kirsten Donovan and Frances Kerry)