Yemeni security officials say inter-militia fighting has flared up at the airport in the southern coastal city of Aden, with a government-allied helicopter gunship firing on fighters in the area, killing three.

They say Sunday that troops from the presidential guard who are backed by the United Arab Emirates have surrounded the facility, now closed for three days due to the fighting. The officials spoke on condition of anonymity because they weren't authorized to speak to journalists.

Yemen's second largest city and once its commercial hub, Aden was intended to showcase the return of President Abed Rabbo Mansour Hadi, who had been exiled for a period in Saudi Arabia during Yemen's civil war that began in 2014. But forces loyal to him have yet to bring the city stability.