ADEN, July 4 (Reuters) - Yemen"s Houthi movement on Sunday carried out a rare missile strike on a southern region that has seen renewed infighting between forces allied to a military coalition led by Saudi Arabia, three government sources said. The attack on a military base in Abyan, which two of the sources said killed at least two soldiers and injured over 20, comes as the recognised government and a separatist group both mass fighters in the area while Riyadh moves to ease tensions. The Southern Transitional Council (STC) has been vying with the Saudi-backed government for control of the south. The Houthis, who ousted the government from the Yemeni capital, Sanaa, in late 2014, largely hold the north. There was no immediate comment from the Houthis, who are trying to seize the government"s last northern stronghold in gas-rich Marib while also keeping up cross-border attacks on Saudi cities. Instability in the south further complicates stalled efforts led by the United Nations and backed by the United States to secure a nationwide ceasefire needed to end more than six years of war in Yemen that have caused a dire humanitarian crisis. Saudi Arabia, which has been hosting talks between the STC and President Abd-Rabbu Mansour Hadi"s government, said on Friday that the nominal allies had agreed to stop political, military, security and other escalations threatening a power-sharing deal struck in 2019, state news agency SPA reported. The two sides have yet to redeploy troops out of Aden and other southern regions as the Saudi-brokered pact stipulates. STC forces, which are backed by the United Arab Emirates, patrol Aden and have taken over several government buildings. The coalition intervened in Yemen in March 2015 in a conflict largely seen in the region as a proxy war between Saudi Arabia and Iran. It has been in military stalemate for years.