* Rival claimants eye lucrative port revenues
* Fighting raises fears of broader Somali clan warfare
* West, neighbours worry Islamists could exploit conflict
A clan leader opposed by Somalia's federal government has strengthened his grip on Kismayu after three days of fighting against rival militias battling for control of the strategic southern port city, residents said on Sunday.
Scores are feared to have been killed in clashes since Ahmed Madobe, head of the Ras Kamboni militia, was chosen in May by a regional assembly to preside over the Jubaland region, where the port lies. He now appears to have extended his control.
Madobe's election had prompted rival claims to the regional presidency, including a clan leader viewed as backed by the Mogadishu government, Barre Hirale. The fighting has raised worries it could spark broader clan warfare across Somalia.
The African Union peacekeeping force, AMISOM, said the city was now calm and its troops had intervened to facilitate talks between rivals, although it said its mission was not to mediate.
"Most of my relatives have been killed today," Faiza Nur, a mother of seven, told Reuters by telephone, without giving numbers. "I hear the sound of gunshots far out to the outskirts. I understand Ras Kamboni now controls all of Kismayu."
The fate of Kismayu is viewed as a test of Mogadishu's skill in building a federal system of government in a nation riven by two decades of conflict and still fighting Islamist rebels who were driven from power by African troops.
The government has said it is ready to compromise but has not spelled out how. Diplomats with a close knowledge of the Kismayu situation say Mogadishu is expected to back down and let Madobe hold the presidency, but only in an interim capacity.
A mother of five, Safia Abdulle, said from Kismayu: "This is the third day we are indoors. The children are very hungry but we cannot go out to buy food. We have no routes to flee."
Residents said later on Sunday that gunfire had stopped, but said they were still too frightened to go outside.
Controlling the port is a lucrative prize for clan leaders, bringing with it revenues generated from port taxes, charcoal exports and levies on arms and other illegal imports.
Residents had said on Saturday they saw more than 20 bodies of those killed in fighting. Hirale told Reuters the death toll of fighters and civilians was at least 50 from the street battles that had erupted on Friday.
Given the clashes and poor communications, it was impossible to obtain a clear death toll. Dozens of people have been reported killed in earlier flare-ups since May.
"We are trying to facilitate their talks, but we are not there to mediate," Colonel Ali Aden Houmed, spokesman for AMISOM in Somalia, said by telephone, adding that African troops had intervened to restore calm which he said now prevailed.
Hirale said from Kismayu that Kenyan forces had deployed but said they had helped Madobe's Ras Kamboni militia. The AMISOM spokesman denied this, saying African troops were neutral.
Madobe is seen as close to Kenya, which has played a key role clearing Islamists from the southern port that lies near Kenya's border. Nairobi acknowledges no such alliance and says its aim with the African forces is to restore peace in Somalia.
Regional and Western powers worry a slide back into conflict would hand the ousted al Shabaab Islamist militants a chance to regroup and spread their militancy beyond Somalia's borders.