CAIRO (Reuters) -Sudan's warring factions fought heavy clashes in parts of the city of Bahri on Friday, residents said, a day after both sides welcomed a new mediation effort that seeks to end a three-month war.

The fighting that broke out on April 15 has driven civilians out of the wider capital region - consisting of the cities of Khartoum, Bahri, and Omdurman - and triggered ethnically motivated attacks in the Darfur region.

Regional and international mediation efforts have so far failed to end the fighting and U.N. officials have said Sudan could slide into civil war.

The latest mediation attempt was launched in Egypt on Thursday. Both the army, which has close ties to Egypt, and the RSF paramilitary group welcomed the effort.

But four residents of northern Bahri told Reuters they woke to heavy early morning clashes between the two sides, apparently centred around the Halfaya bridge.

While the RSF quickly fanned out across the capital in the early days of the conflict, the army has focused on air and artillery strikes that have done little to change the scene.

The army has conducted more ground operations in recent weeks, particularly in Omdurman.

The Bahri residents said they heard air strikes, artillery fire, and gunshots, continuing into the afternoon.

An army source said the army had succeeded in pushing the RSF out of neighbourhoods in the far north of the city in the morning, but the RSF said in a statement they were able to defeat the forces and claimed to kill hundreds.

In a statement the Sudanese army said it had launched ground operations in all three cities of the capital and that it had been successful, acknowledging some losses in Bahri but calling the RSF number inflated.

Residents of the wider capital area reported a communications outage for several hours in the morning.

Other eyewitnesses reported clashes around an army base in southern Khartoum as well.

(Reporting by Nafisa Eltahir in Cairo and Khalid Abdelaziz in DubaiEditing by Frances Kerry)