ADEN, June 24 (Reuters) - Clashes between brigades of the main southern separatist movement in Yemen killed two fighters and wounded 15 people, including civilians, in the port city of Aden, security sources said on Thursday. Aden is the interim seat of Yemen"s Saudi-backed government and has seen rising tensions between the government and the Southern Transitional Council (STC) over control of the city and wider south. The Houthi movement holds most of the north. Repeated gunfire was heard on Wednesday night in Aden"s densely populated district of Sheikh Othman, residents told Reuters. A fire broke out at a building of the education ministry in the area. The fighting, which raged for two hours, erupted when one of the brigades manning a checkpoint attempted to disarm another convoy, the sources said. They said it stopped when STC leader Aidarous al-Zubaidi, ordered both sides to withdraw. Videos on social media showed fighters, armed with AK-47 assault rifles, running in crowded streets. Reuters could not independently verify the footage. A military coalition led by Saudi Arabia has been battling the Iran-aligned Houthis for more than six years but multiple factions are also vying for power. STC and the internationally recognised government are nominal allies under the coalition but its forces have twice seized Aden during the conflict, prompting Saudi Arabia to broker a fragile power-sharing deal in 2019. The two sides have yet to redeploy troops out of Aden and other regions in the south which the pact had stipulated. STC forces, which are supported by Riyadh"s partner the United Arab Emirates, patrol the city and have taken over several government buildings, including the offices of the state news agency. Instability in Aden would further complicate United Nations-led peace efforts to secure a ceasefire needed to end the war that has killed tens of thousands of Yemenis and left millions facing famine. read more The coalition intervened in Yemen in March 2015 after the Houthis ousted the government from the capital Sanaa. The group says it is fighting a corrupt system and foreign aggression.